diff --git a/app/services/collection_resources_service.rb b/app/services/collection_resources_service.rb
index 42667bb78..5116c788b 100644
--- a/app/services/collection_resources_service.rb
+++ b/app/services/collection_resources_service.rb
@@ -20,13 +20,7 @@ class CollectionResourcesService
   end
 
   def file_exists_on_s3?(file)
-    url = "https://#{@storage_service.configuration.bucket_name}.s3.amazonaws.com/#{file}"
-    uri = URI.parse(url)
-
-    response = Net::HTTP.start(uri.host, uri.port, use_ssl: uri.scheme == "https") do |http|
-      http.request_head(uri)
-    end
-    response.is_a?(Net::HTTPSuccess) || response.is_a?(Net::HTTPRedirection)
+    @storage_service.file_exists?(file)
   end
 
   def upload_collection_resource(filename, file)
diff --git a/app/services/storage/s3_service.rb b/app/services/storage/s3_service.rb
index 0cd4a1f20..e6776df0b 100644
--- a/app/services/storage/s3_service.rb
+++ b/app/services/storage/s3_service.rb
@@ -43,6 +43,13 @@ module Storage
       @client.head_object(bucket: @configuration.bucket_name, key: file_name)
     end
 
+    def file_exists?(file_name)
+      @client.head_object(bucket: @configuration.bucket_name, key: file_name)
+      true
+    rescue Aws::S3::Errors::NotFound
+      false
+    end
+
   private
 
     def create_configuration
diff --git a/spec/features/collection_resources_spec.rb b/spec/features/collection_resources_spec.rb
index aaf4b30d4..643f3537e 100644
--- a/spec/features/collection_resources_spec.rb
+++ b/spec/features/collection_resources_spec.rb
@@ -7,7 +7,7 @@ RSpec.describe "Collection resources" do
   before do
     allow(CollectionResourcesService).to receive(:new).and_return(collection_resources_service)
     allow(collection_resources_service).to receive(:upload_collection_resource)
-    allow(collection_resources_service).to receive(:get_file_metadata).and_return({ "Content-Type" => "application/pdf", "Content-Length" => 1000 })
+    allow(collection_resources_service).to receive(:get_file_metadata).and_return({ "content_type" => "application/pdf", "content_length" => 1000 })
     allow(user).to receive(:need_two_factor_authentication?).and_return(false)
     sign_in user
   end
diff --git a/spec/helpers/collection_resources_helper_spec.rb b/spec/helpers/collection_resources_helper_spec.rb
index e50dd334b..31033d997 100644
--- a/spec/helpers/collection_resources_helper_spec.rb
+++ b/spec/helpers/collection_resources_helper_spec.rb
@@ -115,10 +115,8 @@ RSpec.describe CollectionResourcesHelper do
     end
 
     before do
-      WebMock.stub_request(:head, /https:\/\/core-test-collection-resources\.s3\.amazonaws\.com\/2023_24_lettings_paper_form.pdf/)
-        .to_return(status: 200, body: "", headers: { "Content-Length" => 292_864, "Content-Type" => "application/pdf" })
-      WebMock.stub_request(:head, /https:\/\/core-test-collection-resources\.s3\.amazonaws\.com\/2023_24_lettings_bulk_upload_template.xlsx/)
-        .to_return(status: 200, body: "", headers: { "Content-Length" => 19_456, "Content-Type" => "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" })
+      allow(storage_service).to receive(:get_file_metadata).with("2023_24_lettings_paper_form.pdf").and_return("content_length" => 292_864, "content_type" => "application/pdf")
+      allow(storage_service).to receive(:get_file_metadata).with("2023_24_lettings_bulk_upload_template.xlsx").and_return("content_length" => 19_456, "content_type" => "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
     end
 
     it "returns component items" do
@@ -146,10 +144,8 @@ RSpec.describe CollectionResourcesHelper do
     end
 
     before do
-      WebMock.stub_request(:head, /https:\/\/core-test-collection-resources\.s3\.amazonaws\.com\/2023_24_lettings_paper_form.pdf/)
-        .to_return(status: 200, body: "", headers: { "Content-Length" => 292_864, "Content-Type" => "application/pdf" })
-      WebMock.stub_request(:head, /https:\/\/core-test-collection-resources\.s3\.amazonaws\.com\/2023_24_lettings_bulk_upload_template.xlsx/)
-        .to_return(status: 200, body: "", headers: { "Content-Length" => 19_456, "Content-Type" => "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" })
+      allow(storage_service).to receive(:get_file_metadata).with("2023_24_lettings_paper_form.pdf").and_return("content_length" => 292_864, "content_type" => "application/pdf")
+      allow(storage_service).to receive(:get_file_metadata).with("2023_24_lettings_bulk_upload_template.xlsx").and_return("content_length" => 19_456, "content_type" => "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
     end
 
     it "returns component items" do
diff --git a/spec/requests/collection_resources_controller_spec.rb b/spec/requests/collection_resources_controller_spec.rb
index fb8b7ab6f..d7735746c 100644
--- a/spec/requests/collection_resources_controller_spec.rb
+++ b/spec/requests/collection_resources_controller_spec.rb
@@ -2,7 +2,7 @@ require "rails_helper"
 
 RSpec.describe CollectionResourcesController, type: :request do
   let(:page) { Capybara::Node::Simple.new(response.body) }
-  let(:storage_service) { instance_double(Storage::S3Service) }
+  let(:storage_service) { instance_double(Storage::S3Service, get_file_metadata: nil) }
 
   before do
     allow(Storage::S3Service).to receive(:new).and_return(storage_service)
@@ -49,6 +49,7 @@ RSpec.describe CollectionResourcesController, type: :request do
       before do
         allow(Time.zone).to receive(:today).and_return(Time.zone.local(2025, 1, 8))
         allow(user).to receive(:need_two_factor_authentication?).and_return(false)
+        allow(storage_service).to receive(:file_exists?).and_return(true)
         sign_in user
       end
 
@@ -71,6 +72,7 @@ RSpec.describe CollectionResourcesController, type: :request do
 
       context "when files are on S3" do
         before do
+          allow(storage_service).to receive(:file_exists?).and_return(true)
           get collection_resources_path
         end
 
@@ -110,8 +112,7 @@ RSpec.describe CollectionResourcesController, type: :request do
 
       context "when files are not on S3" do
         before do
-          WebMock.stub_request(:head, /https:\/\/core-test-collection-resources\.s3\.amazonaws\.com/)
-          .to_return(status: 404, body: "", headers: {})
+          allow(storage_service).to receive(:file_exists?).and_return(false)
           get collection_resources_path
         end
 
@@ -141,8 +142,7 @@ RSpec.describe CollectionResourcesController, type: :request do
 
       context "when the file exists on S3" do
         before do
-          WebMock.stub_request(:get, /https:\/\/core-test-collection-resources\.s3\.amazonaws\.com/)
-          .to_return(status: 200, body: "file", headers: { "Content-Type" => "application/pdf", "Content-Length" => 1000 })
+          allow(storage_service).to receive(:get_file_io).and_return("file")
           get download_mandatory_collection_resource_path(log_type: "lettings", year: 2025, resource_type: "paper_form")
         end
 
@@ -153,8 +153,7 @@ RSpec.describe CollectionResourcesController, type: :request do
 
       context "when the file does not exist on S3" do
         before do
-          WebMock.stub_request(:get, /https:\/\/core-test-collection-resources\.s3\.amazonaws\.com/)
-            .to_return(status: 404, body: "", headers: {})
+          allow(storage_service).to receive(:get_file_io).and_return(nil)
           get download_mandatory_collection_resource_path(log_type: "lettings", year: 2024, resource_type: "paper_form")
         end
 
@@ -189,8 +188,7 @@ RSpec.describe CollectionResourcesController, type: :request do
 
       context "when year is in editable_collection_resource_years but not in displayed_collection_resource_years" do
         before do
-          WebMock.stub_request(:get, /https:\/\/core-test-collection-resources\.s3\.amazonaws\.com/)
-            .to_return(status: 200, body: "file", headers: { "Content-Type" => "application/pdf", "Content-Length" => 1000 })
+          allow(storage_service).to receive(:get_file_io).and_return("file")
           get download_mandatory_collection_resource_path(log_type: "lettings", year: 2026, resource_type: "paper_form")
         end
 
@@ -262,9 +260,10 @@ RSpec.describe CollectionResourcesController, type: :request do
   describe "PATCH #update_mandatory_collection_resource" do
     let(:some_file) { File.open(file_fixture("blank_bulk_upload_sales.csv")) }
     let(:params) { { collection_resource: { year: 2024, log_type: "sales", resource_type: "bulk_upload_template", file: some_file } } }
+    let(:collection_resource_service) { instance_double(CollectionResourcesService) }
 
     before do
-      allow(UploadCollectionResourcesService).to receive(:upload_collection_resource)
+      allow(CollectionResourcesService).to receive(:new).and_return(collection_resource_service)
     end
 
     context "when user is not signed in" do