In the meantime I'm wiser on this topic. I checked the relevant fuses and relais:
Still no success so I was going to change the last piece that could cause the problem. A few month ago one of the original HID bulbs was going out (pink light). So I changed both bulbs to the fantasic Amazon / Ebay 50 bucks a pair bulbs. It looks like both of them died more or less at the same time after working fine for 5 months.
When I plugged in the old pinkisch HIDs that came with the car the problem was solved. So lessons learned: You get what you pay for.