Bad experience with CMH Mazda Randburg

Hi guys please help I bought a car at CMH Mazda Randburg in 21 May 2022, after two days I took it back because tire had slow panch nd gear was not working well, I just took one long distance trip with in August the car just switched off nd since August the car is with the mechanic nd instalment is stil deducting..Now they say they can't help me they been sending me cars that I have to choose from after selecting one from their list they always comes back saying I don't qualify... Is been almost 4 month please help what step can I take Because to fix it the machinic needs 50k