http://www.autotechperformance.co.uk/
Although I ended up going locally, I emailed these guys for a quote on work and have been amazed by the response received. What a thoroughly nice chap! Peter was happy to advise on what he thought could be causing my issues, was upfront with [very competitive] costs and even said that if I needed any advice in the future to give him a shout.
IMO service like this is as rare as a redneck with all his teeth, so if you're in need of any work/servicing/key programming etc you could do a lot worse than give them a call.
