I don't know what I am doing right, but apparently it is something, since I recieved another upgrade yesterday/today, ORD-ARN. When checking in at SFO, I received 15A (I think) in EconomyExtra/Y+ (also an upgrade, since I was travelling in booking class M), but in the end I was called to the counter and got a brand new BP for 9G! Am I happy? Yes!