I had my golf remapped by http://www.r-techpower.co.uk/ after reading lots of people saying how good they are. There after sales service is absolutely unreal, so helpful!

Not close to you mind, but then Im in Cornwall so much the same. They travelled 3/4 of the way to me and met up. Also they are pretty cheap.
Have a read on www.golfgtiforum.co.uk
Ive never seen anyone say a bad word against them.