sorry, RetiredFF, you probably are.

you don't say how quickly the sheraton contacted you about the error, but it sounds like it was quite fast...(maybe one day? two? after you booked) and it wasn't a prepaid rate, and we're talking about a stay in january rather than next week...so you're probably pushing your luck.

nevertheless, you may be able to negotiate a slightly better discount rate than 10%...but it sounds like the hotel did the right thing here.