Sounds like you're being fobbed off. Ask a friendly taxi driver to recommend a local diesel specialist to ensure the problem is sorted. Personally, I would never buy a second hand common rail diesel that's out of its guarantee with no idea how it's been driven from new. The engine sensors tend to get clogged up with carbon deposits especially when driven predominantly on stop-start trips and you can't tell if it's ever been misfuelled by previous owners!
Following his excellent performance at Le Mans and the Goodwood Festival of Speed in a Nissan GT-R, up and coming racer Jann Mardenborough won the GP3 support race at the Grand Prix weekend at Hockenheim.