Poor customer service and unsatisfactory work

I am disappointed by the appalling customer service I received from this branch. I took my car in for repairs as authorized by my insurer, the vehicle was repaired unsatisfactorily by the panel beater. I noticed that on the bumper where the repairs were done there was still a gaping . The VIN number on the panel beater's job card card did not match the one on the vehicle and insurance policy, the panel beater advised that the incorrect VIN number was given to them by the insurer. This was not brought to my attention, I was only informed about it when collecting the vehicle. I also noticed a tinge of gold paint on the panel above the passenger rear door (my vehicle is silver), when I queried this, as when I took the vehicle in for repairs this stain was not there. The insurer requested me to submit pictures of the vehicle prior to taking it in for repairs, there was no stain on those pictures. The assessor from the panel beater told me that they cannot be held responsible because this stain was a result of previous paintwork that was done on the vehicle. He further argued that this is something that happens overtime, I then queried why this damage is only evident after the car had been in their possession for repair purposes. The panel beater claims not to be liable for any gold paint, nobody wants to take liability of what happened to my vehicle. To date I have also not received any feedback from the panel beater whether the gaping has been repaired or any further updates on the vehicle. I even went as far as requesting proof from the dealership where I had purchased the vehicle confirming whether there had been any paintwork recorded or done on the vehicle prior to the sale to me. The dealership confirmed in writing that there was no paintwork recorded or done.