A few weeks ago, I was trying to SDC onto an earlier flight. The reservation agent was unable to help me. I ended up getting sent to the "manual reissue desk" where an agent tried to change my ticket. And she had trouble with this. She ended up calling yet someone else who seemed to be able to override something.
But it begs he question... Just what is the Manual Reissue Desk? Can't any agent reissue a ticket?