I have now nearly reached the three-year point on a Mercedes-Benz C180 that I bought from a main dealer at six months old with a three-year warranty and two free services. These have now been had and I am told the next service will be the big one at £600 or more. Would I retain a better resale value at this point by continuing with the main dealer servicing, when there are many professionals who do not charge main dealer rates but are just as efficient? There generally seems to be some reason found that vehicles are found to be less valuable than thought. Your advice would be appreciated.