That is frustrating. Have you tried calling again? I aways find that the third time's the charm
I don't have an answer, just my own anecdotal evidence to contribute. When I was GM I was given automatic economy comfort on KLM upon booking, but I could never manually change the seats until check-in. Sometimes I could move
in to economy comfort on online check-in as well if it hadn't been done automatically when booking. So if his PM is fairly recent, shouldn't the GM status be in the system? Or is that just not how life works =/