On another note, if they refund it to card that no longer exists, my guess is one of two things will happen. Either the bank has the account in some sort of inactive but not completely deleted state, and will likely send a check for the refund to the address on file for the card. Or, the bank will reject the payment, and UA will either send it to the address on file for the payer, if known, or contact you to figure out how to send it.

No sure knowledge of this, but my guesses, anyway. Why not start with the card issuer - tell them your situation and give them the card info, and they Should be able to tell you how they'd handle it based in the card status. Cant hurt at least to give this a shot.