Cam belt fix but an electrical problem?

The timing belt went on my girl friend's 10 year old x reg clio. RAC dropped the car off at a local back street garage. They quoted �550 to put a new belt on. After they installed the belt the car wouldn't start, There appeared to been an electrical fault. The garage arranged to moved the car to another garage where an electrician could find the fault.This garage did find the problem after a 18 hours of labour. The electrical garage said the problem would have been simpler to resolve if the car's electric wasn't in bits. I'm presuming here that the mechanical garage tried to figure out the electrical fault first before passing it onto the electrical garage perhaps trying to do a good deed. The invoice from the electrics comes to �395 which the mechanical garage says he has paid.Making the girlfriends total bill �995 for a car with a px value of �400. My question is what the likely chances that the mechanical garage caused the electrical fault. It was serviced last 6 months ago and there was no work done on the electrics then.