PATHETIC SERVICE PANELBEATERS

my car was send to them for repairs for the bumper and tow bar. it is now 3 weeks later NOW only am I informed that they are still waiting for the bumper but I was informed last week that the bumper was already replaced and that they wait for the tow bar. now I am told that they are waiting for the bumper this is UNACCEPTABLE as it is already 3 weeks and still my car is not fixed.