BMW cedar isle now has my car for 4 months and will not give me any useful information

My car went to BMW cedar isle due to the fact that when trying to start the car sometimes by pushing the start button the car would not start after they had a week to look at the car they tell me the fuel pump is damaged which I was quoted for and agreed to pay for I then get a call to say my car is ready and I can pick it up on arrival the car did not start after the so called faulty part had been changed they then took 2 more weeks and then told me I have a faulty DME (computer box) I agreed to pay for it again on condition that they give me my so called faulty fuel pump as I wanted to take it to get it tested as I did not believe that it was ever faulty they then call me up and told me all my parts have been lost they have agreed not to charge me for the parts they lost but since then my car has been with them now over 3 months they keep telling me they are fixing the car !!!