Live person or not, AMEX customer service often gives terrible advice. A former CSR from AMEX admitted to me that their "book" advised them to give customers any reason whatsoever to deny them their right to a chargeback. Stop talking to these people on the telephone, because telling them on the phone about the double charge does not protect your rights. Send a certified letter to AMEX return receipt requested demanding that the double charge be removed from your credit card. Based on a crummy experience I had years ago, it is very difficult to get a wrong charge removed from an AMEX bill, much harder than it should be under federal law. I am a "former" AMEX customer because of this issue of being incorrectly billed and their unwillingness to fix the matter in timely fashion.

I've never had another credit card company refuse to fix an obvious double bill or send me back to the merchant for an issue like that. There is no reason for it except that AMEX wants to delay you for 60 days, so you lose your right to dispute the bill in writing. Dispute the bill with AMEX now. Sure, try to figure out how to get in touch with the airline. I can't help you with that side of it. But AMEX still has a big responsibility You are not psychic. You don't know who made the error that put the bill through twice. But AMEX can clearly see the same charge put through twice, and they are just wrong to sit on their hands and try to delay fixing the issue.

Good luck. But please take action on this in writing with AMEX now. You have to do this whether or not the airline also contacts AMEX. It is very nice of you to contact the airline, so they can request a fix and not get charged a fee for the chargeback. But if you can't easily contact the airline, it is much more important for you to save yourself being double-billed $7,500 than it is for you to worry about the airline being charged $30 for a chargeback fee. There is such a thing as priorities.