I know someone (not Me) who used a code that they had no ID for, got to the Hotel way after cancellation time and was carded. W/o the ID they said OK we will charge you the reg rack rate and when you fax us in your ID we will refund the difference. So he went on a song and dance and said If you dont trust me then I dont want to stay here. They answered fine, you can leave but since its way after the deadline to cancel you will be charged the rack rate for the room anyway.
He stayed and ended up paying the full rate
So as many have said all over the Forums if you use a Code that you arent entitled to be prepared to have to pay aheck of alot more then you ever would have agreed to in the 1st place.
Post stay I havent heard of anything, But theres always a 1st time for everything