At this point that is what I'd do. Obviously the GM & asst GM have no clue what they're doing & customer care has not been able to get it sorted.

BTW - the parking lot line is ridiculous. We've had examples of CY/RIs sharing the same bldg & it's still considered a walk because they're different properties/brands. The walk policy is in writing on Marriott's T&Cs. Perhaps the OP should provide a copy of it to the GM

Cheers.