OP here. I guess I was annoyed and overreacted. I can easily see why this could be due to incompetence/bugs and not intentional lying. This was a 016 non award ticket. I did HUACA twice but got the same result all 3 times. Tried to talk to UA after I landed in LGA but got sent to AC as I was kind of expecting. The AC flight I was on did leave on time but the next one is delayed but has no seats left in Y.