Taking unacceptably long to fix my car!

I had an accident on the 27th Jan, claimed immediately and only a week later did I hear that the car has been assessed and sent to the Panel Beaters. The car parts were only booked late last week and should have been repaired by today. I called to enquire about the status of the car and my consultant advised me that they ordered the wrong part! NO ONE called to advise me of this and NO apology was offered to me. They have had my car for two weeks now and yet nothing has been done as yet! I am thoroughly annoyed and disappointed!!! This can't possibly be the service they provide their customers! And in the meantime I am stranded without my car!<br> Your urgent assistance in this regard will be greatly appreciated!