just got a call from the workshop...
they did change both Vanos adjustment units on Bank 2 and it seems that this fixed the problem.
I'm happy and frustrated by the same... they probably re-installed covers and sensors correctly this time and they gonna charge me two brand new Vanos....

I will get back the car this evening... I will let you know... but this will be probably more a commercial issue thread now than a tehcnical one...

Cheers and thank you again for your answers guys