Sounds like there's a possible problem with the pump/injector and that it's likely to be the timming injection pump deviation.
My own two-pennorth is forget Landy dealers for this particular problem and go to a diesel injection specialist, look in local yellow pages or similar ...
The model is a 98 xedi swagon. The reason i got auto electrican out was for a minor fault wth reversing light switch. New owner of a landy so lay off with your sarcastic comments