Poor customer service

on the 21/11/14 my car was serviced by mccarthy volkswagen in witbank. my services advisor was Nadene Hills and on that day she called me to come and fetch my car then i did that, on my way home the engine lid appeared then i called them and report the light then they said the system was outdated and the light will disappear.I drove my car for couple of days and it started to misfire which it never had a problem before, i called the dealer and inform them then they said i should bring the car back,i did that and it took them a week and a half to fix the problem then they called that is done. after some few days the EPC sign appeared and the car start to loose power, i called the dealer to report the fault then they told me to bring it for inspection, i did that and they said there was problem wit the spark plugs and change them but the engine light was still on but they said the system is outdated and it cant switch off the light and wont have any effect on the car.After that my warranty was due and i still had a problem wit my car now that am out of warranty i cant repair the engine fault which was not completely fixed by the dealer the time the car was on warranty.