I overheard a request for upgrade at check-in and then heard another (different pax) on board. This was a few years ago on a VS to JNB (I think) when I was in P.E. with them.
The check-in agent tells them: "I'm not authorised to do that, please ask on board."
The cabin crew say, "I'm not authorised to do that, only check-in can do that."
