I reserved a two-night free-stay at the Wendover N...

I reserved a two-night free-stay at the Wendover Nugget Hotel Casino (Dec. 5th and 6th) with a confirmation number provided securing my scheduled stay prior to leaving my house in Clearfield, Utah. When I went to check in I was told I had to go to guest services to get a voucher, although my reservation was confirmed over the phone. Guest services informed me that I did not have any free stay. They even accused me of already using it, as if I was being dishonest. The notice I had with me was from last year but I was approved for this year due to the confirmation I recieved by calling in first.
They acted as if I didn't speak to the right people. I said that is the phone number they provide and asked if any other phone number is provided for the consumer to call. They said no there was not. As I told them, this is a violation on their end because my stay was confirmed regardless of how they operate and whether or not the notice I had with me was from another year or not. If I was not allotted the free-stay applying to this year, then why was I approved for the two-night free stay per confirmation provided when I made the reservation? No type of compensation or accommodations were offered on their behalf, as if they were not accountable for what their services promised to provide me.
Ironically, the 'free-stay' had to be cancelled, which I did after this dispute on Thursaday December 5th. I thereafter left and returned to Clearfield.