American Express two weeks ago: We need to send you a new card with a new number.
American Express tonight: We declined a transaction from [DragonCon host hotel] because they used your old card number. LOLZ
Me, frantically calling Amex: Can you please, please, please, please let that transaction go through?! If you don't, I will lose the room!
Amex: Sorry. You'll have to get in touch with the merchant.
I might have just lost my #DragonCon hotel room because Amex can't fix this problem.