I also have a problem with my C15 citroen champ.

Headlight bulbs - put a multimeter on the battery when the car has been running for a while and is still running. If its about 14.8V then the alternator may be cooking the bulbs. Also make sure that you are fitting branded high quality bulbs as the cheap imports last only tens of hours. If they are H4 bulbs, which I think they are, make sure that your dipped beam is going off when the high beam come on, as if they are both on for prolonged periods, the bulbs overheat and the elemtns break down very quickly. It can be indicative of the stalk not turning the dipped beam off.