Refunds on a credit card feed appear as adjustments to the credit card, but you can tie them to a specific vendor. That way both the credit card register and the vendor account are accurate.

We are moving to a credit card whose feed is unsupported. This functionality does not appear to exist. Either the vendor is correct and the credit card register is wrong or vice versa.

https://kb.blackbaud.com/knowledgebase/articles/Article/105393

It seems that the functionality exists to attach a vendor to an "adjustment." We just need an interface that will do it. It would be very, very helpful.