Hi Mercman62
We tried the local Merc dealer (I use them for my GLC all the time for service) and they were not interested in the job - they said it wasn't their type of thing the engine would either need removing and rebuilding or they could source a reconditioned engine - either way the advice was they dont do work like that and we should look for a more affordable solution.
Anyway car has been sold for spares now so thanks for your reply but this thread can be closed by an admin if they wish.
Richard