I have found variations of up to 40% for the VAG std service at main dealers. I live in Cheltenham and work in Oxford and have found that asking at Gloucester, Cheltenham, Cirencester and Oxford main dealers for the same service (50k miles) resulted in 40% difference in proce for the same work. I went for the cheapest (which at 50k miles was Oxford ~ £200) 2 months later, for the misses GTI ed30, Cirencester was miles cheaper, just depends how much work they have on and how hungry they are. Cheltenham VW (my local) are always prices as per the std VW menu, as a result they only get warranty work ;-)