Renault Sa sold the faulty car ,which they cannot fix it and refuse to refund my installment .

i bought a Renault Ko;eos from one of the Renault sa business partnership (multi franchise ) it was faulty car , i bought in december and just could drive for a month , it has a gearbox problem. i have a case with renult customer care regards my problom. my car was at renult workshop but they couldnt fix the car. after 3 months ,which the car still is in the workshop. they send me email which they cannot replace the car , they get get back the car but they wont refund my expense and installment which is unfair. because the knew the car is faulty ,they are already replace the gearbox twice and they still cant fix the car but they don't want to payback my money. i wont recommend renult sa to anyone.they dont care about the customer, they just want to sell the faulty car. the car is kolos 2020 model.