Failed after sale service

I bought a used car with them June this year, there were so many hiccups, of which I was happy and impressed with how they sorted some of them out, however when they delivered my car, it came with a chipped wind screen, and they promised to get it replaced, we arranged for it, I had to pay a driver to take it to their dealership only to find the person that was supposed to fit it wasn't available, they promised to send someone to my house up until to date, nothing has happened