Ok a bit more info, I have been talking to a friend working at VWG maintenance. Basically any car that is on fixed servicing cannot be changed to variable servicing per se. But you can still put the long life oil in and run a longer servicing interval. This does bring up 2 problems, first the car wont tell you when the next service is due since it still thinks its on fixed service schedule (so you will have to guess) and second it will invalidate your warranty if it is still valid.
SEAT's that came from the factory with QG1 were a mistake, they are still on fixed servicing. If a car is changed from variable to fixed it cannot be changed back, as Simon said. Though that does beg the question as to what the difference is between QG0 and QG2