OP I came to make a post about this very topic. Stayed at the Marriott Regents Park recently and experienced the same treatment. Upon check in they didn't offer me my welcome gift choice just said I get 1000 points. I also did not use mobile check in. I asked about the guarantee, they said I don't get that choice there only points and would not honor the $100. I escalated with the GM and they honored the guarantee. They gave me a ...... exchange rate which was irritating but small victories, I guess.

I checked out and came back a week later and same thing. Employee refused to honor it. This time manager wouldn't budge. I just let it go because honestly it's not worth the frustration.

I was hoping to see if anyone else has had success contacting corporate.