Was on AA127 DFW-PVG last week, applied SWU request 5 months ago so I was #1 on list when checking in at counter at DFW. I went to lounge afterwards until 10 minutes before boarding time, but when I arrived at the gate I found out they cleared the #2 passenger on list with the only J seat left.

I asked them why and the agent said they paged me 3 times at the gate and also to the lounge (which is not true as there was no broadcast heard at all) and no one showed up so they gave the upgrade to #2 passenger. As it was the last J seat and the person already got on the plane there was nothing that can be done.

Question, is this the correct procedure? I was always under the impression that my boarding pass will beep at the gate when scanned and they'll issue the new one, but I never knew I needed to be there early (than boarding time) to prepared to be paged. Is there anything I can do in terms of complaint to AA?