Sueing a student.

I am a student who was involved in a minor bumper bashing incident this last December with my farm bakkie/pickup-truck. Unfortunately we cannot insure the bakkie/pickup-truck due to it being too old. In a bumper bashing that wasn't my fault, yet cannot prove it, outsurance is now attempting to sue me because of the damages to their clients vehicle. This is the first time I've heard of an insurance company sueing the person who is not the client for damages, and its not just excess, its damages in full, its in excess of R20 000. I am willing to pay the excess but not the full damages. To my knowledge insurance companies insure cars for this very reason. Yet I'm being sued for the full amount of the damage. I am a student that does not have this type of money. Its a tough situation to be in.