pre-owned car with underlying problems

I bought an i20 hyundai on promo as preowned at hyundai eastrand, it had 27k on the clock needless to say I was very happy as the dealer was very helpful and supportive to add to my excitement I finally got my first car plus it was my favourite brand. The car made a hissing noise so I returned it 2days later I was told by the manager that its normal i20 1.2s do that fast foward 5 weeks later the car broke down while I was at work. I had it towed to hyundai boksburg now to my shock the problem will take 4 weeks to fix and to my outrage the hissing noise the car made when I bought has finally caught up with me so I returned the car for replacement or refund as I dont look forward to driving a stripped down new car with a gear box problem im then told it wont happen because the 7 day cooling off period is over needless to say im angry coz I wont be having a car for 4weeks!!!! While im paying for it. I really need a lawyer because iv been sold a faulty car! Hyundai is an international brand but right now it feels like a tuck shop because of this terrible service! Please beware when buying a preowned car because they are usually pushing away their damaged goods!