Which has nothing to do with your status. This is just the regular rebooking you can do traveling on a Plus ticket. Of course they will then ask for a fare difference.

As I said, it worked for me a couple of times.

Last time I had a family emergency and I asked the gate agent of the flight two hours earlier if I can get on the flight since a close relative was admitted into the hospital with a serious medical condition.

I offered to pay a fare difference between my Go ticket I was holding and the Plus ticket but they just made it work. This is not the recommendation to try this to get on an earlier flight for free since it is not convenient to wait another hour in the airport.

I was very happy they made the exception on that day which allowed me to see my relative before serious surgery but if people start exploiting this or similar stories I guess they will cut off such exceptions.

Some other times I just asked as my incoming longhaul was early and was lucky, but that's quite some time ago (1,5 years?)