Sorry to hear about the credit card issue. There really is no reason for them not to take your card. As we all know, a standard-issue Mastercard or Visa works just about anywhere in the world. AA has no problem when I call the AA office in Tokyo, from Australia, and give them my US Amex number.
As suggested, try calling back and if they still refuse, ask why. I can understand them wanting the security code from the card (they always want that anyway) but there is no reason not to take a non-U.S. card. If they persist, point out that they are in violation of their own rules, as set out their "Agency Reference" material on AA.com.
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September 14, 2004
As a reminder, per the ARC Industry Agent's Handbook section 8.0, agents must honor any credit card brand that is presented as payment for an ARC traffic document provided the ticketing carrier accepts that credit card brand as a valid form of payment. Discrimination among credit card brands is prohibited.
Anyone acting as an agent for American Airlines is required to accept all of the following credit cards:
American Airlines Credit Card
American Express
Diners Club
Discover
JCB
Mastercard
UATP
Visa