I have used VW Windrush Maidenhead service department for my 2003 VW Touareg for over two years.
They do free annual safety checks for existing customers and free checks for new customers too in order to introduce them to service staff - so go and introduce yourself and your car!
They can provide the factory build sheets for your car too - I found an extra I didn't know about.
VW Windrush have done major repairs as well as annual maintenance.
They give discounts on cars over 4 years old, and guarantee parts for 2 years and labour for 1 year on repairs they undertake.
I always price check against other garages and they will nearly always price match or otherwise get close enough that I stay with them and keep VW stamps in the service book.
Several contributors to the UK VW Touareg forum www.mytreg.com also use them, some travelling quite a distance past other VW dealers, and all speak well of the service they get.
So, VW Windrush - friendly, knowledgeable, good banter and price conscious. What more can one ask?
And they always clean my very dirty car [it is a 4x4 that gets properly off road] very nicely too!!
A big thumbs up from me.
FYI - The service department is separate from the sales location shown on the map linked to the address above but is easily reached less than 5 minutes from J8/9 on the M4 or less than 15 minutes from J4 on the M40.