unothorised garages in sheffield, england

hi everybody!

I would be gratefull if anyone could tell me if he/she knows of any non-authorised/oficial garages that service mgf's in sheffield, england (you know, good, honest and cheap) , cause I've just about had enough with the prices and the service you get from the official dealers( eg. price of my last annual service £1360!!!)

thanx in advance

Mark