Originally Posted by
dmodemd
I also wonder how the ticket was re-instated if it was supposedly cancelled. This had to have been done with a conversation between the passenger and United and with an explanation of the seat being gone.
She almost certainly didn't cancel her 'ticket'. She canceled the reservation on that flight, most likely by moving to another flight.
The ticket (and more specifically, the coupon for that leg) would remain valid, and moving back to the original flight would be a trivial task for any UA agent.
As someone that has previously lost an upgrade by accidentally changing flights on the app, I can see exactly how this could occur. (In my case I realized immediately and they were able to move me back to the flight within minutes - but without my cleared upgrade).