What Should I Do About This Vet?

I would tell her to talk to the receptionist that I had made the arrangement with about the money. She is not a very caring vet that would not discharge your cat for a extra 22.50 that she wanted to charge plus the extra 40.00 to keep the cat when the cat could be back at her house instead of a cage. All she cares about is money not animals and I would probably tell her that. All you care about is money not animals. Especially since you gave her the details on your card which was fair of you to offer.