I have this problem, though not as severe as yourself, it slips about an inch on the wheel after just about 5 miles, but doing a longer drive doesnt seem to make it slip any more than that.
Mentioned it when I was in for its first service, and they said that they would need the car for the day so that one of the techs could take it for a drive, probably when they collect or deliver another car - really didnt fancy that idea.
Mentioned it to my local VW indie (good friend), and he basically said, if you can live with it, then live with it cos you may get it back worse from the monkeys at the dealership.
So, I`m living with it unless it gets a lot worse.