Wow, that's a shocker. Technically, the hotels are individually owned, but Marriott also has its name on them and manages the majority of them (I'm not sure if Phuket is a managed property.). To wash their hands of the situation is beyond silly.
Look, I have to be perfectly honest: When I've had good experiences at a particular chain and encounter one problem child, I usually just accept it and move on. But in this case, the company wasn't even willing to stand behind its product. If it were me, I'd be giving Starwood a call.
Mike