Amex Travel -and- Platinum Travel Service can -both- be reached by telephone at separate numbers.
Amex Travel (Orbitz) : 1-800-297-2977; outside US, 1-312-980-7807 Published
here:
If you booked your travel with American Express Travel and you need to change/cancel a booking,...if you booked your flight within the last 24 hours or have a departure date within the next 3 days please call us at 1-800-297-2977 for the U.S. (outside of the U.S. at 1-312-980-7807).
Platinum Travel: 1-800-443-7672 Published
here:
As a Platinum CardŽ member, you also have access to Platinum Travel Service, an exclusive full-service travel agency standing by 24 hours a day to assist you with all your travel needs. To modify, confirm, or cancel an existing reservation with Platinum Travel Service, please call 1-800-443-7672.