diff --git a/lib/pact_broker/client/hal/entity.rb b/lib/pact_broker/client/hal/entity.rb
index 5f9c3761..e78ec725 100644
--- a/lib/pact_broker/client/hal/entity.rb
+++ b/lib/pact_broker/client/hal/entity.rb
@@ -1,12 +1,18 @@
-require 'uri'
+require 'erb'
 require 'delegate'
 require 'pact_broker/client/hal/link'
 
 module PactBroker
   module Client
     module Hal
+      class RelationNotFoundError < ::PactBroker::Client::Error; end
+
+      class ErrorResponseReturned < ::PactBroker::Client::Error; end
+
       class Entity
-        def initialize(data, http_client, response = nil)
+
+        def initialize(href, data, http_client, response = nil)
+          @href = href
           @data = data
           @links = (@data || {}).fetch("_links", {})
           @client = http_client
@@ -33,14 +39,20 @@ def follow(key, http_method, *args)
           Link.new(@links[key].merge(method: http_method), @client).run(*args)
         end
 
-        def _link(key)
+        def _link(key, fallback_key = nil)
           if @links[key]
             Link.new(@links[key], @client)
+          elsif fallback_key && @links[fallback_key]
+            Link.new(@links[fallback_key], @client)
           else
             nil
           end
         end
 
+        def _link!(key)
+          _link(key) or raise RelationNotFoundError.new("Could not find relation '#{key}' in resource at #{@href}")
+        end
+
         def success?
           true
         end
@@ -49,8 +61,8 @@ def response
           @response
         end
 
-        def fetch(key)
-          @links[key]
+        def fetch(key, fallback_key = nil)
+          @links[key] || (fallback_key && @links[fallback_key])
         end
 
         def method_missing(method_name, *args, &block)
@@ -66,12 +78,29 @@ def method_missing(method_name, *args, &block)
         def respond_to_missing?(method_name, include_private = false)
           @data.key?(method_name) || @links.key?(method_name)
         end
+
+        def assert_success!
+          self
+        end
       end
 
       class ErrorEntity < Entity
+
+        def initialize(href, data, http_client, response = nil)
+          @href = href
+          @data = data
+          @links = {}
+          @client = http_client
+          @response = response
+        end
+
         def success?
           false
         end
+
+        def assert_success!
+          raise ErrorResponseReturned.new("Error retrieving #{@href} status=#{response ? response.code: nil} #{response ? response.raw_body : ''}")
+        end
       end
     end
   end
diff --git a/lib/pact_broker/client/hal/http_client.rb b/lib/pact_broker/client/hal/http_client.rb
index 0b78723b..c2dd4f30 100644
--- a/lib/pact_broker/client/hal/http_client.rb
+++ b/lib/pact_broker/client/hal/http_client.rb
@@ -4,7 +4,7 @@ module PactBroker
   module Client
     module Hal
       class HttpClient
-        attr_reader :username, :password, :verbose
+        attr_accessor :username, :password, :verbose
 
         def initialize options
           @username = options[:username]
@@ -56,7 +56,7 @@ def perform_request request, uri
 
         class Response < SimpleDelegator
           def body
-            bod = __getobj__().body
+            bod = raw_body
             if bod && bod != ''
               JSON.parse(bod)
             else
@@ -77,6 +77,7 @@ def success?
           end
         end
       end
+
     end
   end
 end
diff --git a/lib/pact_broker/client/hal/link.rb b/lib/pact_broker/client/hal/link.rb
index 452a9dd5..29dc2322 100644
--- a/lib/pact_broker/client/hal/link.rb
+++ b/lib/pact_broker/client/hal/link.rb
@@ -38,15 +38,15 @@ def name
         end
 
         def get(payload = {}, headers = {})
-          wrap_response(@http_client.get(href, payload, headers))
+          wrap_response(href, @http_client.get(href, payload, headers))
         end
 
         def put(payload = nil, headers = {})
-          wrap_response(@http_client.put(href, payload ? JSON.dump(payload) : nil, headers))
+          wrap_response(href, @http_client.put(href, payload ? JSON.dump(payload) : nil, headers))
         end
 
         def post(payload = nil, headers = {})
-          wrap_response(@http_client.post(href, payload ? JSON.dump(payload) : nil, headers))
+          wrap_response(href, @http_client.post(href, payload ? JSON.dump(payload) : nil, headers))
         end
 
         def expand(params)
@@ -57,21 +57,19 @@ def expand(params)
 
         private
 
-        def wrap_response(http_response)
-          require 'pact_broker/client/hal/entity' # avoid circular reference
+        def wrap_response(href, http_response)
+          require 'pact/hal/entity' # avoid circular reference
           if http_response.success?
-            Entity.new(http_response.body, @http_client, http_response)
+            Entity.new(href, http_response.body, @http_client, http_response)
           else
-            ErrorEntity.new(http_response.body, @http_client, http_response)
+            ErrorEntity.new(href, http_response.raw_body, @http_client, http_response)
           end
         end
 
         def expand_url(params, url)
-          new_url = url
-          params.each do | key, value |
-            new_url = new_url.gsub('{' + key.to_s + '}', URI.escape(value))
+          params.inject(url) do | url, (key, value) |
+            url.gsub('{' + key.to_s + '}', ERB::Util.url_encode(value))
           end
-          new_url
         end
       end
     end
diff --git a/spec/lib/pact_broker/client/hal/entity_spec.rb b/spec/lib/pact_broker/client/hal/entity_spec.rb
index 49873e81..935c5efb 100644
--- a/spec/lib/pact_broker/client/hal/entity_spec.rb
+++ b/spec/lib/pact_broker/client/hal/entity_spec.rb
@@ -32,7 +32,7 @@ module Hal
         }
       end
 
-      subject(:entity) { Entity.new(pact_hash, http_client) }
+      subject(:entity) { Entity.new("http://pact", pact_hash, http_client) }
 
       it "delegates to the properties in the data" do
         expect(subject.name).to eq "a name"
@@ -60,6 +60,32 @@ module Hal
         end
       end
 
+      describe "assert_success!" do
+        context "when the response is successful" do
+          it "returns the entity" do
+            expect(entity.assert_success!).to be entity
+          end
+        end
+
+        context "when the response is not successful and there is no response" do
+          subject(:entity) { ErrorEntity.new("http://pact", pact_hash, http_client) }
+
+          it "raises an error" do
+            expect { entity.assert_success! }.to raise_error ErrorResponseReturned, "Error retrieving http://pact status= "
+          end
+        end
+
+        context "when the response is not successful and there is a response" do
+          let(:response) { double('response', code: 200, raw_body: "body") }
+
+          subject(:entity) { ErrorEntity.new("http://pact", pact_hash, http_client, response) }
+
+          it "raises an error" do
+            expect { entity.assert_success! }.to raise_error ErrorResponseReturned, "Error retrieving http://pact status=200 body"
+          end
+        end
+      end
+
       describe "can?" do
         context "when the relation exists" do
           it "returns true" do
@@ -74,19 +100,47 @@ module Hal
         end
       end
 
+      describe "_link!" do
+        context 'when the key exists' do
+          it 'returns a Link' do
+            expect(subject._link!('pb:provider')).to be_a(Link)
+            expect(subject._link!('pb:provider').href).to eq 'http://provider'
+          end
+        end
+
+        context 'when the key does not exist' do
+          it 'raises an error' do
+            expect { subject._link!('foo') }.to raise_error RelationNotFoundError, "Could not find relation 'foo' in resource at http://pact"
+          end
+        end
+      end
+
       describe 'fetch' do
-        context 'when the key exist' do
+        context 'when the key exists' do
           it 'returns fetched value' do
-            expect(subject.fetch('pb:provider')).to be do
-              {href: 'http://provider'}
-            end
+            expect(subject.fetch('pb:provider')).to eq("href" => 'http://provider')
           end
         end
+
         context "when the key doesn't not exist" do
           it 'returns nil' do
             expect(subject.fetch('i-dont-exist')).to be nil
           end
         end
+
+        context "when a fallback key is provided" do
+          context "when the fallback value exists" do
+            it "returns the fallback value" do
+              expect(subject.fetch('i-dont-exist', 'pb:provider')).to eq("href" => 'http://provider')
+            end
+          end
+
+          context "when the fallback value does not exist" do
+            it "returns nil" do
+              expect(subject.fetch('i-dont-exist', 'i-also-dont-exist')).to be nil
+            end
+          end
+        end
       end
     end
   end
diff --git a/spec/lib/pact_broker/client/hal/link_spec.rb b/spec/lib/pact_broker/client/hal/link_spec.rb
index e5ed7634..efe14591 100644
--- a/spec/lib/pact_broker/client/hal/link_spec.rb
+++ b/spec/lib/pact_broker/client/hal/link_spec.rb
@@ -10,7 +10,7 @@ module Hal
       end
 
       let(:response) do
-        instance_double('PactBroker::Client::Hal::HttpClient::Response', success?: success, body: response_body)
+        instance_double('PactBroker::Client::Hal::HttpClient::Response', success?: success, body: response_body, raw_body: response_body.to_json)
       end
 
       let(:success) { true }
@@ -48,7 +48,7 @@ module Hal
         end
 
         it "creates an Entity" do
-          expect(PactBroker::Client::Hal::Entity).to receive(:new).with(response_body, http_client, response)
+          expect(PactBroker::Client::Hal::Entity).to receive(:new).with("http://foo/{bar}", response_body, http_client, response)
           do_run
         end
 
@@ -64,7 +64,7 @@ module Hal
           let(:success) { false }
 
           it "creates an ErrorEntity" do
-            expect(PactBroker::Client::Hal::ErrorEntity).to receive(:new).with(response_body, http_client, response)
+            expect(PactBroker::Client::Hal::ErrorEntity).to receive(:new).with("http://foo/{bar}", response_body.to_json, http_client, response)
             do_run
           end
         end
@@ -102,6 +102,10 @@ module Hal
         it "returns a duplicate Link with the expanded href with URL escaping" do
           expect(subject.expand(bar: 'wiffle meep').href).to eq "http://foo/wiffle%20meep"
         end
+
+        it "returns a duplicate Link with the expanded href with URL escaping for forward slashes" do
+          expect(subject.expand(bar: 'wiffle/meep').href).to eq "http://foo/wiffle%2Fmeep"
+        end
       end
     end
   end