I have used Nigel for a few bits personally and he is very professional indeed. Only uses MB genuine. He is the only indie I have any experience of so couldn't comment for price but I was very pleased with the work they did on my CLK and my father's troublesome W202 that kept jumping out of Drive for seemingly no reason. It was a wheel speed sensor but Nigel did go through all of the common corrosion points in the wiring loom (had half the interior out to do it). Made me think that he really knows his Mercs.
