Car not yet fixed

My Mom is really not happy about the service that she has received from Momentum, her car was involved in an accident, the body was fixed but when it came back the car was not driving properly and kept losing power and jerking. The car has been at the panel beaters for 5 weeks and they keep giving us the run around, and keep saying that it is not accident related. It’s funny that their saying this but don’t hesitate when it comes to taking money from my Mom for their services and now they choose to do this. I think we’ll have to take the legal route at this point.