I was downgraded on a NYE reservation at StR Abu Dhabi 2 years ago. Making matters worse (IMO) is that the hotel actually tried to claim it was an upgrade... and not being able to get on wifi until I checked in + ~10 min for the system to recognize me, I wasn't able to verify at the front desk.

Starwood CCS worked with me to get the SNA refunded to my account and the hotel also tossed some goodwill points my way (16k IIRC?). Ultimately, it was still profitable for the hotel -- since I'm sure they sold "my" suite for $1000+ for NYE -- so I still have a little sour taste in my mouth that the hotel "got away with it," but CCS took care of me.