Disgusting and unacceptable service from SA underwriters

SA underwriters have to be the worst insurer one can come across. My mother had a minor accident which left her side mirror damaged and had a few scratches. Upon the claim being approved she was sent to their chosen service provider MAG repairs who then gladly took the vehicle in for repairs. Two weeks after the vehicle was with their service provider we followed up on the progress of the repairs and were told that MAG had requested an additional quote to the insurer to approve. Only at this point was my mother informed that since the vehicle was in their possession it now cannot start because of a "faulty ignition system" and they will not cover that. When we enquired what caused that to happen MAG arrogantly told us that we must g to Mercedes Benz and ask them. This is a car that had no mechanical or electrical issues prior to the accident and even after as she drove the car for a month while waiting for panel beaters to reopen after the December holidays. Upon informing SA underwriters of this they then advised us of the obvious that they won't cover it as it's not accident related. Whatever happened to the car happened while it was in the possession of their panel beaters. As we speak they are requesting my mother to return the courtesy car without having resolved the above. Their claims Consultant keeps making empty promises with impunity and no accountability. The apparent ignition fault according to them is going to cost R15 000 to repair and they are now keeping the car and expecting my mother to cover that??? Absolutely disgusting service received and I'm in the process of taking this matter up with the ombudsman as they need to account for their service providers actions