STUCK WITH A CAR I CANT DRIVE

I bought myself a 2013 polo vivo with 36000km the end of April month. I only enjoyed the car for 6 weeks after purchase then the car died, was towed in at vw lichtenburg for repairs though even after collection of the car still gave problem as it jecks and shows water warning lamp while driving.. I took it back and I still got the car back like that and is just parked not driving.. I explained to the sales person who sold me the car but couldn't help me and spoke to the sales manager whom am still waiting for his response to help me.. I asked him to get me another car or even cancel the contract since well am no longer happy with the car nor interested in driving it. Sales manager says they can't get me another car except for a courtesy car while they repair it because it will now have a settlement that they can't pay for.. I am not looking forward to drive it anymore as i don't trust that it will ever be reliable for me. Now I am struggling with transport and the purpose of me buying the car is that it's essential for me at work. I need another car or cancel the contract . Can't pay 71 months left of instalment with a problematic car like this