Because OP cancelled the tickets, UA will simply respond to DOT that it would have fixed the issue had OP given it the chance, but OP didn't, do no fix. End of complaint.

Bet OP could have had this taken care of in 10 minutes had he called Web Support in the first instance as recommended upthread. They can see the original reservation, reconstruct the fare, override the system and ticket.

Wait until something goes wrong with LX tickets. OP will then learn the meaning of "that is not possible."