My currently installed headlight assemblies have both kinds of bulb. I have removed them and found the part # but I am still having issues with which ones I need.
Are you saying that your currently installed headlight assy's have both a halogen and an HID bulb installed in them, or are you saying that those are the two optional assy's available?
If you remove your headlight assy's there should be a part # on each of them.
It's really unfortunate that German manufacturers spec'd "biodegradable" wiring in their headlight assemblies (I have the same problem too), and it's probably too late to take any sort of action about it now. However, have you looked into repairing the wiring, either yourself, which is not an easy job, or professionally, which, although may be costly, but would probably still be cheaper than buying new assemblies.