Knock-Knock-Knocking Engine Double price... Bad Price....

Bought an engine fore Hyundai Getz. The engine came with a knocking sound. Went back to them and they first claimed it was the Lifters, then they claimed it's the sims, which the engine does not have and then they claimed the lifters bolt were stripped by our mechanic (3 months later) and we must pay a reduced rate of R1800 then they found the one piston was running skew and we must pay another R3000 (reduced). We confronted two of the owners of SA Auti\oparts and they claim we are arrogant and none if the issues was their responsibility under their 'warranty' agreement! I lodged a complaint with the SA Consumer Council.