Sorry, I don't have any experience with any, but I know Grayswood Cars specialise in VW, Audi, BMW and Mercedes, I tend to use Arnolds Garage in Shottermill, service there is generally pretty good, hope that helps
I can vouch for Lee at Witley station garage real decent HONEST mechanic knows his stuff ive been taking my noble to him for last 4 years or so no is 01428685330