Let me say again what I think is happening is United is trying to get away with all of these violations of DOT regulations by painting a picture of what happened that is UNTRUE. I think this based on their statements about the issue. It seems like they're trying to make a case that the "correct" price was displayed all the way through and somehow the computer made an error at the end and issued tickets without checking for or deducting the payment. This is NOT WHAT HAPPENED. UNITED HAS LIED TO DOT TO GET AWAY WITH THIS. Everyone make it clear that the price displayed was "4 miles + taxes/fees" at all stages of the ACTUAL PURCHASE (after specific flights were selected) and that United successfully charged the monetary part and had access to and could have deducted the miles portion at will like always. Be sure to explain these things in your complaint so it becomes clear to DOT that United lied to them to get away with this.