The experiences above mirror mine. It happens every single time. I have a trip the first week of July booked and upgraded (took about 20-30 minutes once I got through just for the agent to grab the seats). It still hasn't been reissued. I fully expect to be spending time on the phone the end of next week to get them to push it through.
The amount of time spent by agents, and supervisors, on this has to be astounding in the aggregate. Even if there were sinister motives present from a corporate standpoint, I just don't think the ROI is there to make them this hard to use.