Worst service ever!!!!!

I took my car in for the 120000km cambelt service on the 12 October 2019 at the McCarthy VW Constantiakloof dealership. I was called to come fetch my car at just before 12 but when I got there they were still busy working on my car and only got my car at 14:30 without the car washed.....we sat a whole 2 hours 30 minutes waiting for our car and we dropped the car at 7 the morning....a week after the service the car dies while driving and we could not get the car started again...we had to get a towing service to tow the car back to the dealership. They did an investigation and found that the sprocket cracked/broke. I was then told that is not a result of the service. I refused to pay for it because clearly the technician working on my car was inadequate seeing it took him about 7 hours to do my service as I was told he was dedicated to my car and did no other car service for that day. In my research I found that the sprocket breaks due to a faulty or snapped tensioner belt which is the exact part they replaced a week ago. It has been 4 days now and still no feedback...I have called numerous times and then I am told the service manager will call me soon for the way forward but still no call...I called now again and they put me through to the service manager and held on the line just for the phone to put down in my ear...this is not the first time I an getting this bad service from them and it seems like its in the McCarthy group because we received bad service from the Westgate branch too. It does not surprise me seeing that there are quite few complaints on Hello Peter for both the above mentioned dealerships. Their ads and motto says For peace of mind service your car at an agent but I have lost all my trust in service agents. Word of advice do not make use of McCarthy dealerships...even their new car deals are shady. They should definitely get bad score in the trust index...they even removed their branch from Hellopeter to ignore customer complaints