CHM Group dishonest about the car condition

I bought a car at CMH Group pre. used at Umhlanga branch 31st November 2019, after all the paper work was done and given the car key, after leaving the Dealership we started hearing noises while driving the car, we immediately returned the car to the Dealer, sales person Quintin drove the car and heard the noise but insisted is the engine sound, Hyundai i20 2015 model, I was not satisfied I drove off but within few minutes I returned the car again because the noises did not give comfort, then Dealership owner took the car for a drive he also heard those noise and could not explain what is wrong with the car, when we returned he gave the car to one of his sales person to drive the car he also heard those noises but couldn't tell what is wrong with the car, after all this drama I've decided I will not take the car in such condition they should fix the car.

on Monday the 2nd December the Dealership owner gave me a call to indicate that they took a certain part from Hyundai i20 2019 model and put in the car and the car is fine now, I then told him I am not comfortable to drive a car like that, since I saw him opening the bonnet and clearly stated that I am not a mechanic I don't understand what they talking about,

I am cancelling the whole process, that's when he indicated that he will sue me.

kindly assist this Dealership **** about the condition of the car.