Hi Clemens
I'm sure it is a custom bolt as it is hexagonal. There is probably a threaded insert which now has the broken bit of your bolt still in its threads. Get this back out (There are many cheap tools available to do that) and get a new bolt from the dealer.
It was probably broken by forgetting to undo the studs nearest the doors when lowering the hood which puts strain on the pivot. I have done this myself a couple of times, don't worry, and I am expecting the same problem as you have at any time.
