unacceptable service

I bought a brand-new car from Renault in Fourways on the 15 September and 4 days later I advised them of a problem I am experiencing. I have taken the car in 4 times now and this problem has not even been sorted. They are apparently waiting for Head Office to get back to them. It does not take you 2 and half months to sort out a problem. I am furious with the service.