I have tried the email address before. Only a robot answer returned, with instruction to the Marriott gift card page - it does not solve any issue nor provide any assistance.

I did not try the phone number so no idea how that would work. FD has access to Help Desk phone support but often is a very long wait and seemingly fairly difficult process (coaching from afar on what to do), It boils down to whether the property is willing to try. When using GCs I now always make it clear at check in, and ask them to process the payment right there, if anyone knows how to do it. At a newly opened Aloft the FD asked to make a copy of the GC, said the night manager would figure out how to do it. What they did was to put a 0.10 charge to the AMEX and put the rest on the GC. After that they refunded the 0.10 a few days later.

It truly is hit or miss in using the GCs. Because of this I really do not want to hoard GCs any more, promotion or not. I will only add to the existing holdings when the balance goes down to less than a couple hundred.