SagePay Payment Integration in .NET -- 2

I would prefer if someone has already worked on SagePay API to send customer payment request.

I’m ready to plug SagePay’s payment processing into my existing vb.net application that runs on the classic .NET Framework. Everything else in the platform is already live; what’s missing is the secure hand-off to SagePay and the callback logic that confirms a successful transaction.

Scope of work
• Build a clean, commented module (class library or set of classes) that sends payment requests to SagePay and handles the full response cycle—authorisation, AVS/CV2 checks and the final OK or error message.
• Single-currency only, so no exchange-rate logic is required.
• I’m not using SagePay for refunds, reversals or recurring billing right now—just the one-off purchase flow.
• The code must fit into a .NET Framework solution (Visual Studio) and compile without changes to my existing architecture.
• Use the official SagePay API endpoints, SHA-encrypted signatures and any nonce/timestamp requirements so we remain PCI-compliant.

Deliverables
1. Compilable source code (C# or vb.net) targeting .NET Framework.
2. App.config/Web.config snippets showing the needed keys, vendor name and endpoint URLs.
3. A short read-me or markdown guide that walks me through installing test credentials, running a successful test transaction and switching to live mode.
4. Confirmation that a test payment completes in the SagePay sandbox, with the result data deserialised and logged.

Acceptance criteria
– I compile, drop in my own vendor credentials and see a “Payment successful” result via the SagePay simulator.
– No hard-coded secrets in the source.
– Any third-party NuGet packages are listed with exact versions.

If you’re comfortable with SagePay’s protocol and seasoned in .NET Framework, this should be a focused integration task rather than a full build.