my xenons have been flickering recently so I swapped the bulbs and the same side is still flickering so I bought a new ballast.

Replaced the ballast and it didn't work. I put the old ballast back and now the xenon doesn't work at all. I did try the new ballast on the other side (which works fine) and the it didn't work and xenon still working with the old ballast.

OK i think the new ballast is faulty but....in order to find the right ballast:-

do I need to just look for a 35w, 12v unit?

Do I need to find one specific for h7r bulbs? The one ive just bought states its for a d2s/d2r bulb but apart from that its identical and my existing leads do fit the new ballast.

Ive checked the fuses but I can't find one for headlights. I have a 2004 325ci m sport coupe. Any help would be great.

Ive been told by HIDS UK that I have an aftermarket kit and not the OEM......how do I know if thats the case?