diff --git a/Gemfile b/Gemfile
index 2f5d85e9..0995f11f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,6 @@ gem "aws-sdk-s3"
 gem "bootsnap", require: false
 gem "gds-api-adapters"
 gem "gds-sso"
-gem "gds_zendesk"
 gem "govuk_app_config"
 gem "govuk_sidekiq"
 gem "kaminari"
@@ -22,6 +21,7 @@ gem "plek"
 gem "sentry-sidekiq"
 gem "user_agent_parser"
 gem "whenever", require: false
+gem "zendesk_api"
 
 group :development do
   gem "listen"
diff --git a/Gemfile.lock b/Gemfile.lock
index 29bd506f..7f3e931d 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -156,9 +156,6 @@ GEM
       rails (>= 7)
       warden (~> 1.2)
       warden-oauth2 (~> 0.0.1)
-    gds_zendesk (3.7.0)
-      null_logger (~> 0)
-      zendesk_api (>= 1.37, < 4.0)
     globalid (1.2.1)
       activesupport (>= 6.1)
     google-protobuf (4.27.2)
@@ -738,7 +735,6 @@ DEPENDENCIES
   factory_bot_rails
   gds-api-adapters
   gds-sso
-  gds_zendesk
   govuk_app_config
   govuk_sidekiq
   kaminari
@@ -762,6 +758,7 @@ DEPENDENCIES
   user_agent_parser
   webmock
   whenever
+  zendesk_api
 
 BUNDLED WITH
    2.5.9
diff --git a/config/initializers/gds_zendesk.rb b/config/initializers/gds_zendesk.rb
index eec76a55..ac891fb0 100644
--- a/config/initializers/gds_zendesk.rb
+++ b/config/initializers/gds_zendesk.rb
@@ -1,15 +1,17 @@
 require "yaml"
-require "gds_zendesk/client"
-require "gds_zendesk/dummy_client"
+require "zendesk_api"
+require "zendesk/dummy_client"
 
+GDS_ZENDESK_URL = "https://govuk.zendesk.com/api/v2/".freeze
 ZENDESK_ANONYMOUS_TICKETS_REQUESTER_EMAIL = ENV["ZENDESK_ANONYMOUS_TICKET_EMAIL"] || "api-user@example.com"
 
 GDS_ZENDESK_CLIENT = if Rails.env.development?
-                       GDSZendesk::DummyClient.new(logger: Rails.logger)
+                       Zendesk::DummyClient.new(logger: Rails.logger)
                      else
-                       GDSZendesk::Client.new(
-                         username: ENV["ZENDESK_CLIENT_USERNAME"] || "abc",
-                         password: ENV["ZENDESK_CLIENT_PASSWORD"] || "def",
-                         logger: Rails.logger,
-                       )
+                       ZendeskAPI::Client.new do |config|
+                         config.url = GDS_ZENDESK_URL
+                         config.username = ENV["ZENDESK_CLIENT_USERNAME"] || "abc"
+                         config.password = ENV["ZENDESK_CLIENT_PASSWORD"] || "def"
+                         config.logger = Rails.logger
+                       end
                      end
diff --git a/lib/zendesk/dummy_client.rb b/lib/zendesk/dummy_client.rb
new file mode 100644
index 00000000..3638633d
--- /dev/null
+++ b/lib/zendesk/dummy_client.rb
@@ -0,0 +1,63 @@
+require "zendesk_api/error"
+
+module Zendesk
+  class DummyClient
+    attr_reader :ticket, :users
+
+    def initialize(options)
+      @logger = options[:logger]
+      @ticket = DummyTicket.new(@logger)
+      @users = DummyUsers.new(@logger)
+    end
+  end
+
+  class DummyTicket
+    attr_reader :options
+
+    def initialize(logger)
+      @logger = logger
+    end
+
+    def create!(options)
+      @options = options
+      if should_raise_error?
+        @logger.info("Simulating Zendesk ticket creation failure: #{options.inspect}")
+        raise ZendeskAPI::Error::RecordInvalid.new(body: { "details" => "sample error message from Zendesk" })
+      else
+        @logger.info("Zendesk ticket created: #{options.inspect}")
+      end
+    end
+
+  protected
+
+    def should_raise_error?
+      description =~ /break_zendesk/ or comment =~ /break_zendesk/
+    end
+
+    def description
+      @options[:description]
+    end
+
+    def comment
+      @options[:comment][:value] unless @options[:comment].nil?
+    end
+  end
+
+  class DummyUsers
+    def initialize(logger)
+      @logger = logger
+    end
+
+    def search(_attributes)
+      []
+    end
+
+    def suspended?(_user_email)
+      false
+    end
+
+    def create_or_update_user(new_attributes)
+      @logger.info("Zendesk user created or updated: #{new_attributes.inspect}")
+    end
+  end
+end
diff --git a/spec/helpers/zendesk_test_helpers.rb b/spec/helpers/zendesk_test_helpers.rb
new file mode 100644
index 00000000..a782390d
--- /dev/null
+++ b/spec/helpers/zendesk_test_helpers.rb
@@ -0,0 +1,27 @@
+require "json"
+
+module Zendesk
+  module TestHelpers
+    def stub_zendesk_ticket_creation(ticket_properties = nil)
+      stub = stub_request(:post, "#{zendesk_endpoint}/tickets")
+      stub.with(body: { ticket: ticket_properties }) unless ticket_properties.nil?
+      stub.to_return(status: 201, body: { ticket: { id: 12_345 } }.to_json,
+                     headers: { "Content-Type" => "application/json" })
+    end
+
+    def stub_zendesk_ticket_creation_with_body(body)
+      stub_request(:post, "#{zendesk_endpoint}/tickets")
+        .with(body:)
+        .to_return(status: 201, body: { ticket: { id: 12_345 } }.to_json,
+                   headers: { "Content-Type" => "application/json" })
+    end
+
+    def expect_zendesk_to_receive_ticket(opts)
+      stub_zendesk_ticket_creation_with_body("ticket" => hash_including(opts))
+    end
+
+    def zendesk_endpoint
+      "https://govuk.zendesk.com/api/v2"
+    end
+  end
+end
diff --git a/spec/lib/zendesk_dummy_client_spec.rb b/spec/lib/zendesk_dummy_client_spec.rb
new file mode 100644
index 00000000..6cf02a82
--- /dev/null
+++ b/spec/lib/zendesk_dummy_client_spec.rb
@@ -0,0 +1,43 @@
+require "zendesk/dummy_client"
+
+module Zendesk
+  describe DummyClient do
+    context "when a ticket has been raised" do
+      let(:ticket_options) { { opt1: "val1" } }
+
+      it "logs the ticket details" do
+        logger = instance_double(Logger)
+        expect(logger).to receive(:info).with("Zendesk ticket created: #{ticket_options.inspect}")
+
+        client = described_class.new(logger:)
+        client.ticket.create!(ticket_options)
+      end
+
+      it "can simulate failures, triggered by a specific description or comment" do
+        logger = instance_double(Logger)
+        client = described_class.new(logger:)
+        expect(logger).to receive(:info).with(/Simulating Zendesk ticket creation failure/).twice
+
+        expect {
+          client.ticket.create!(description: "break_zendesk")
+        }.to raise_error(ZendeskAPI::Error::RecordInvalid)
+
+        expect {
+          client.ticket.create!(comment: { value: "break_zendesk" })
+        }.to raise_error(ZendeskAPI::Error::RecordInvalid)
+      end
+    end
+
+    context "when a user has been created" do
+      let(:options) { { email: "a@b.com" } }
+
+      it "logs the user details" do
+        logger = instance_double(Logger)
+        expect(logger).to receive(:info).with("Zendesk user created or updated: #{options.inspect}")
+
+        client = described_class.new(logger:)
+        client.users.create_or_update_user(options)
+      end
+    end
+  end
+end
diff --git a/spec/support/gds_zendesk_helpers.rb b/spec/support/gds_zendesk_helpers.rb
index 474d4d42..54c48834 100644
--- a/spec/support/gds_zendesk_helpers.rb
+++ b/spec/support/gds_zendesk_helpers.rb
@@ -1,12 +1,5 @@
-require "gds_zendesk/test_helpers"
-
-module ZendeskRequestMockingExtensions
-  def expect_zendesk_to_receive_ticket(opts)
-    stub_zendesk_ticket_creation_with_body("ticket" => hash_including(opts))
-  end
-end
+require "helpers/zendesk_test_helpers"
 
 RSpec.configure do |c|
-  c.include GDSZendesk::TestHelpers
-  c.include ZendeskRequestMockingExtensions
+  c.include Zendesk::TestHelpers
 end