I created a VDP VEPSS project app and took a look at the dashboard's sandbox menu on the left side. I don't see any Test Data available for use at this time. So I went ahead and I started sandbox testing using the VDP Playground application (this application is downloadable in the same left hand side menu under "Assets"). For test data, I navigated to the VEPSS API Reference page here - https://developer.visa.com/capabilities/visa-europe-payment-stop-service/reference
I used the Code Explorer //Body (the blackish greyis rectangular box on the right side of page) and I received a successful 200 OK Response for VEPSS API Stop Instruction Create API. Below you will see my VDP Playground screenshot of my sandbox test for VEPSS API Stop Instruction Create API, Stop Instruction Retrieve API. I've also included the successful Request, Response and Response Header.
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