Flight 17 hrs delayed. Then upon boarding in seat 1F they said they had zero room for any carry on luggage. They reluctantly let me keep one item after a heated discussion. They took my second item, a typical roller bag and said they would gate check it to pick up on the jet bridge at the end of the flight. They didn't give me a tag or receipt for it. The woman insisted she did, and that if I asked again for one I would be removed from the aircraft. When I arrived at my destination my bag was nowhere to be found. I eventually called the luggage office at the airport and they had one "mislabeled" bag that they didn't know who it belonged to. I made an online complaint and received a robot reply "Sorry we didn't live up to your expectations." I called the ExPlat line and they said all they do is reservations/bookings, that they don't take any complaints. I then filed a DOT complaint.