Hotwire Your reservation is not confirmed Internet

Confirmed car rental reservation and took full payment to Alamo than refused to rent to me at counter. Made reservation with Hotwire and paid $42,20 in advance for confirmed reservation. When I arrived at Birmingham airport and went to Alamo car rental counter I was refused a rental. I was told I am on the do not rent list. I've never heard or this or know why I am on the list. Alamo would not tell me why I am on this list or give me any contact to call. I was stranded and had no car rental. I called Hotwire and they said sorry nothing they would do. Please help me prevent this from happening again or to others