I was flying RDU-IAD-ORD, and due to overbooking, volunteered to take a direct (slightly later) flight on AA to ORD (it was one of the last UA flights anywhere that day, and I think the last AA flight), got free ticket according to the deal. The original flight left and we (me + 3 other people) went to the AA gate where we were told that UA "pulled back" our tickets and they won't issue BP. Both gate agents (UA & AA) were not too helpful - we had to run between the gates because they couldn't figure a way to call each other. It was worse than it sounds, as basically we forced the UA agent to issue us ptix to use on AA, only like 2 minutes before the AA gate closed and we had to sprint back to the gate to catch it. It took me like 20 minutes to calm down afterwards, as it was a really close call.

Is anyone able to tell me - what went wrong? We all felt cheated by the UA, because after offloading us they basically left us to fend for ourselves... Is there any point in escalating this issue further?