Delay in replacing oil pipe/injectors wastes fuel

I took my car for a service at BMW Northcliff Auto in September 2015 at their initiation and oddly, it was the 3rd time in as many months. This is incidentally where I bought my car in late December 2012 but immediately after that third service, I noticed that the car was releasing a thick fog of white smoke every morning or every time if it had been parked for more than 2 - 3 hours. I immediately notified my service advisor (Carlo) and when I took it in in October, they indicated that it needed to be booked in overnight for observation and thereafter be left at their service workshop for another 2 to 3 days to do the repairs/ part replacement. I asked for a courtesy car because in my line of work, I need to be mobile and I then asked to be put on a waiting list. I followed up with them in late October and again in November with a view to establish as to when would it be fixed because since then my fuel consumption has shot up the roof. In November, I was told that Carlo had left and I was to speak to Annaline who, I must add has not been helpful because not only didn't she return my calls but I was not put on the waiting list. I have visited the dealership several times in person.