Thanks for the replies. I'm almost there, but . . . . according to expertflyer the flight is G9 E1 N0. I have two separate bookings I want to upgrade, one with one person and the other with two people. Both bookings show an upgrade price of 470 euro. So now, if I go forward with the singular booking, I come to the payment page. If I try with the two person booking, I get the error page. Is this because it's E1 and N0 and I want to upgrade two people? I would think it would then show a higher price for the G9 booking class, no?