Last time I had an upgrade clear after I had already checked in, OLCI had an aneurism and told me to see an agent. Further attempts to do anything with that itinerary were met with "problem with itin... blah, blah, blah... you must see an agent."

I probably should have called 1P reservations at that time, but thought the DEN agents would have no problem fixing it for me... That was a mistake. Front-line premier (excluding the 1K/UGS desk) CSRs at DEN epitomize the term moat-dragons without exception in my experience. I personally thought throwing my bag as hard as humanly possible onto the conveyor was also a nice touch.