Car problems

We bought a used car at Volkswagen Rusterburg Mastercard a Nissan Extrail on 2019 Sept 24 n only drove it for 3 months 4 it 2 not to start, we took the car for fixin only to b told during diagnostic that it was involved in an accident which was not disclosed and it requires R36000 to be fixed.after long discussions n ups n downs the garage fixed it and it came back end of January 2020 to be stuck again on February til date.. now the garage blame us for the car being damage n doesn't want to take accountability for it of which it does the same thing it was doing before being fixed.. The garage is doing the financing.. now the question is we paying for a car that is not starting what must we do Now,?? and really disappointed in Supergroup as a reputable company..