Thanks for the advice. I will pop into the dealership at the weekend and see what they say then.
I really couldn't believe what I was hearing when I got through to the (dis)service department.
I did ask if I was better off letting the car stall out and call VW assist to recover me. The response was if the fault was covered under warranty it would be a free fix but if not, work would be charged at the standard rate...
Judging by the responses here there is a problem somewhere with idling engines, such a rookie issue to have.