VW Hatfield Bryanston *********** and not helpful

My car (VW POLO 1.4 Trendline 2013) has been giving me problems of not starting, idling abnormally, losing power and switching off in traffic, jerking while driving. I took my car to VW Hatfield Bryanston so many times , my car still at this point gives me the same problems,actually its gotten worse. I have paid R645 for spark plugs, for nothing and my car is still not fixed. I have to keep taking my car back and on top of that, they insist that I pay them pterol money to test drive my car YET THEY TOOK R645 FROM ME AND DIDNT FIX THE PROBLEM AND SECONDLY IF THEY COULD FIX THE PROBLEM I WOULDNT HAVE TO KEEP GOING BACK,so why must I keep paying and inconveniencing my life because of their incompetence. My car is a VW, they should know how to fix their cars as they are VW. I am still sitting with this problem today, how do they expect me to travel my kids around with a car that is not functioning properly. I have spoken to the manager and to the workshop Foreman Kirtan Daya who is not willing to go the extra mile for me even though i have been inconvenienced too many times by VW. I have also emailed the principal dealer and theres no interest in helping me as I have had no reply.