Totally dissatisfied customer!

I have previously had very disappointing service delivery from this company and I am yet again in the same situation! Technostar have had my car since the 25 August and it is still not ready and I have just been told by Lunga that I'll probably only get it at the end of next week!! I'm not prepared to continue waiting and will be going in to see them and the car myself on Monday. I have just been told that it is being polished so cannot understand how it will take another week to complete. Such poor service is shocking. As the car is a Merc there is very limited choice as to where I can take it so Technostar is the last place I would choose. I have a friend who has had similar bad service. The vehicle did not have major damage. A door had to be replaced and Lunga said they had to wait for the door to arrive and would probably only do so on Thursday 4/8. I phoned Mercedes who are on the adjacent premises and was told it would be there the following afternoon Tuesday 2/8. I phoned on Wednesday 3/8 and was told they were waiting for delivery to which I responded " you can walk next door and fetch it." When I was promised a phone call I generally had to phone myself! I will collect the car on Monday and remove it in whatever state it is.