My dad (now deceased) used to use a chap called Val at Ace Motor Repairs at Coxide, for years. His car was a Merc and I honestly don't know how good they are but he seems a decent chap. Please mention Derek and me if you follow up.
Bill
Ian also works for Sea start in Plymouth and recently serviced our Volvo KAD32 and Outdrive for an extremely resonable price. Highly recommended and a thoroughly nice bloke who is very very helpful too.