Amex has 2 travel systems that produce a lot of confusion, as can be seen here.

FHR has the Nam Hai Hotel Hoi An, which has a 7 day cancellation policy, and then a single night cost of cancellation after that. If this isn't what you booked, then you did not use FHR.

Parts of the non-FHR site show FHR properties, and I never use that due to this possible confusion.

I just managed to log in to see rates for this hotel, so not everyone's having login problems.

As a note, the FHR site is actually not built by Amex - they outsource this to a company that should be better at this task than they actually are.