I seem to be having a week of bad luck with (some) hotels. I had a reservation here for Saturday, but their system didn't accept my credit card for some reason. I got a relatively unfriendly worded email which I can sort of understand so I called up to give them my other credit card and their system wouldn't accept that either. The Soviet army-esque woman at the end of the phone informed me that as a result they'd be cancelling my reservation and I have to look somewhere else to stay. AMEX assure me that my cards are both fine and that I have a nearly 6-digit spending allowance left.

I routinely have basic issues with Marriott stays, but being told I'm not allowed to stay takes the biscuit.

Edit: AMEX called to follow up to say that although the request from Marriott was made, the Marriott Regent Park's authentication system is out of date so AMEX won't let them pull funds from anyone until they fix it.