I personally dont see Marriott allowing a hotel to call a $99 rate a glitch and then change it, $19.90 certainly (under our laws there is the "common man theory" - would someone assume this rate is a mistake, certainly most people would assume $19.90 in NYC isn't correct....$99 - not so much)...if the hotel is trying to change a $99 rate I would encourage the OP to contact Guest Relations to discuss the matter further