Misleading salesmen and dikra reports

I bought a car for a total of R 335 000 in April at the silverlakes branch of which their Dakra report indicated it was in good condition, I paid them R5400 to have it serviced and R 14 000 for warranty, on my way home the car gearbox malfunctioned and I returned it . They refused to take it back and insisted on having it fixed. They have been fixing it since,I have already paid 2 installments without using it.