Not happy with work done

I had problem with Thekwini toyota in Kokstad i took my vehicle for engine overhaul in 2015 but the vehicle was never right after the engen was done. I reported the matter to them they said i must bring the vehicle back . It came out again on the same condition now they say i must pay on top of the amount i paid which was R40,000 now they say i must pay R68,000 please help me