I've managed to find someone to examine the engine and the first thing he noticed was that I had a Bosch filter rather than a Mercedes one. He reckons that there might have been condensation in the engine itself and this might have damaged the filter. Are there any experts out there who might have an opinion one way or the other?

I bought my Mercedes Sprinter van new 5 years ago and had 3 yearly services with the same garage up to 42,000 miles. For the next 2 years up to 75,000 miles I used a local garage in the NW10 area which came highly recommended {had Astons, Bentleys etc in the garage}.... anyway my van broke down and I had it towed there and have since discovered that I need a new engine. I am amazed to be told this as the van has only 75,000 miles on it. The quotes I have been given by 3 different people in the past 36 hours have ranged from £3,500, then £6,000, then £9,000 and now back to £6,000. What I would like to know is if there is a company out there that can investigate or do an inspection to check that official Mercedes parts have been used and also if I can have the oil analysed as I know that using the wrong oil can mess up the engine and void the warranty. Any other advice would be greatly appreciated.