Dont take responsibility to fix a car after 4 mths

I bought a 2010 tiguan tsi in July 2015 from Mccarthy VW. In October a warning lamp came on showing<br> that there is a fault with catalytic converter. I took it nearest VW dealership Ntt King William's Town. Ntt VW checked the car and quoted R6000. This was passed on to Mccarthy and they suggested that i pay 50% and they will also pay 50% and I refused. I asked Motor Finance from Nedbank to intervene and Mccarthy paid the bill and the car was fixed. After 4 days the same warning light came on again i took it back to Ntt VW. They said that the settings of the timing were incorrect. They quoted R5000. Both instances MotorVaps (warranty insurance) declined to pay saying they do not pay mechanical and electrical repairs. The quote again was referred to Mccarthy VW. They have responded. The car is standing for 2 months without being repaired. I am paying instalment and insurance every month i can not use the car. I have asked Motor Finance to intervene because i stlii owe them over R200 000 sothat i may get another car to subsititude this one. I am not getting feedback from all of the involved parties