Mercedes benz is the worst company

My car was ****** and recovered on the 4th August and the panelbeater ordered parts thru mercedes benz the glen. We have been waiting for the parts for too long and they asked mercedes benz the glen to request courtesy car since my car is still on warranty but they later declined it and said the parts is on back order.yesterday I called them and apparently they can not trace the part and they cannot offer me courtesy car and the reason y I do not have a car is because mercedes benz is failling to provide the parts.when you call no one has the answears