Discovery failing to fix my car

My car was booked for the panel beaters on the 2 November on the 4th panel beater needed to paint the front bumper but they couldn't reason being Discovery insurance didn't want to authorize the replacement of lower bumper which is a FACTORY FITTED carbon fibre THAT CAME STANDARD WITH THE CAR. Before they can paint a bumper they need to remove the lower bumper and surely it will break because it's a carbon fibre. The quotation to fix my car was R4400 and my access is R3500 and they don't want to authorize the lower bumper this is a disgrace. All they enjoy is do debit our account every month but failing to deliver their promises.