I gues you're german?.
Anyway, you need to have the cylinder head pulled and the valve guides and
Don't let the dealer or anybody else fool you into just doing the valve seals
without pulling the head, this will fix the problem only for a few month's.
I'm not sure what the average shop out there charges, I charge $ 1,250, parts
and labor, this is what comes with that, valve guides, and seals, clean all the
valves, cylinder head gasket, manifold gaskets, new spark plugs (bosch H9DC),
oil change with filter, and finally a new valve cover gasket.
Also, the upper front timing chain cover will automaticly be resealed, cause
often they have a leak there anyway.