I've heard some shocking stories about main dealers. I had a first hand experience with Audi. I took my A4 in for a service, then about 2 weeks later I needed to change my tensioners, and took it to an Audi specialist as they would do it at about half the price. When the specialist drained my engine he found the oil was very dirty. He showed me the colour of it, there is no way that Audi changed it when servicing, despite ticking the schedule...
Whilst I'm sure the majority of stealers are top quality, I would rather a competent mechanic using OEM parts that relies on the quality of his work for business than a spotty teenager with all the gear & no idea at the main dealers. In my opinion FVWSH doesn't mean sh*t.
If you're in the Bedfordshire area I will happily point you at a decent VAG specialist mate.
Much love