SagePay v3 integration with eCart

Hi

I've been trying to upgrade my client's website to integrate with SagePay v3. I need to get it done by the end of the month or it will stop working. I followed guidance on another thread on the forums and posted a couple of times on that but have been advised by Ray Borduin to start a new thread to avoid confustion with the other posters on that thread.

Where I'm up to:

I've cloned my client's website and associated MySQL database in a subfolder and I'm using this dev site to connect to the SagePay test server for the purpose of testing the integration.

I've downloaded the new version of Protx_VSPForm.php that Ray posted up on the old thread, modified my confirm.php file that sends the order to SagePay, and I can now successfully pass orders to SagePay without the encryption error that I was seeing previously.

However, once the order is placed and I'm returned to my website's order success page, that page is not able to determine the VendorTXCode using $Protx_VSPForm_Bindings["VendorTxCode"]

On the previous thread, Ray asked me to check that I had changed the encryption code on the top line of Protx_VSPForm.php which I have done and it is correct. My understanding is that it would have to be in order to connect with SagePay in the first instance so that I could place the order.

I've attached my copy of Protx_VSPForm.php and also the order_success.php page from my website that is failing to identify the VendorTXCode and hence failing to mark the order as complete in our database.

Sorry if the coding is a bit messy, I'm learning as I go