I think this will get resolved in due time, either by Amex, AA or both. I'd give the process a few weeks to work itself out. However, I'm not sure how a merchant can reverse a refund. I deal with a credit card processing interface and don't see a way to do that in the UI or programmatically, but perhaps other interfaces have a way to void a refund. AA might request you send them a check or might be able to do a miscellaneous charge. Let us know how they eventually resolve this.