To me, it is absolutely ridiculous. If Amex’s IT is so bad that someone fills out an open link form promising a good SUB, Amex should honor it and move on with their lives, and then hire competent coders to prevent this. Taking it out on the customer, and accusing of them for acting in a “nefarious” way is absurd.

I think about those airlines that have mistake fares now and then. They might not honor the fare (sometimes they do, sometimes they don’t). They don’t ban the customer for life for buying a mistake fare.