Originally Posted by
Often1
Still comes back to bottom line that OP did not hold a confirmed Y seat and his F seat had an add/collect due. He could have been treated better, but neither DL nor UA violated DOT's IDB rules.
Correct. And ultimately, it was UA's fault for booking the OP in F on DL. When you get transferred over the new airline is not required to honor the upgrade. It was booked as an economy fare. The agent grabbed the F seat without looking at what add collects may be required to actually ticket in F.