BAD SERVICE/ BAD WORKMANSHIP

I am very unhappy with work that was done on my BMW. I brought my vehicle in on the 07/05, for the timing chain to be replaced, when I came to check on my vehicle on 15/05, the parts which was removed from my engine was laying on my back seat, as a result, there are 3 huge oil stains and it is filthy. I eventually collected my vehicle on 21/05, the oil smell is really unbearable and to top it all, there is smoke coming out of my engine as soon as the car is warmed up, this while I am driving, I do not know what is wrong, I cannot even use my fan on the interior or my air conditioner as the smoke comes inside the vehicle, it is winter now and I cannot use it at all. It is extremely embarrassing as my car was perfect when I brought it in! My fenders on both sides, the areas where the guys were working was still full of dirty oil, my interior was dirty as well, the mats were also full of dirty oil which was stepped in and out. I did not leave my vehicle in that condition and I had to clean this mess up myself!! I am extremely disappointed in the lack of customer service and professionalism this business has, I am referring to your management staff, on arrival of the enquiry I was asked whether I have a warranty and immediately was informed that it is accepted. Prior to collection which was 2 weeks later, I was reminded that I was to follow up with regards to payment from my warranty for work done, this before I even received my vehicle, it seems that MONEY is all that is chased this following poor workmanship. I checked my engine and opened up to see where the smoke was coming from, I noticed immediately that a nut was not replaced either, God only knows what else could be wrong. I now have to fork out additional money out of my pocket to have my car checked again and fixed for the errors or faults, the interior is to be cleaned, my seats and carpets as well. This is I think is so unfair as all my expectations are to be met and as a business, you see that your customer leaves smiling and satisfied with the work done. Never use this business, it is a *******