Failed car repair

I have a complaint with Bidvest McCarthy Nissan Germiston.

On the 29th January 2021, I took my car to the dealer for check-up. My car was not performing as usual. It loses power when driving on open road. The Service Agent called and inform me that technicians identified that the problem was a timing chain. The car remained with the dealer over the weekend for repairs and I was advised that I will get my car the following Monday 01 February 2020. My wife collected the vehicle for me because I was out of the province. The car remained unused until 11 February 2021 when I we came back from KZN. I than drove the car to test it and I realized there and there that the sound/idling of the car on start-up was unusual. I drove the car to Meyersdale to test it and I realized that the performance is still the same (the car still dips) and there was a warning light that appeared. I called Service Agent (Esther) and she advised that I bring the car on the Monday 15th March 2021. On Monday, I brought the car as advised and upon their check-up they discovered that the car had a a damage on a catalytic convertor and there was a cut and welding on the car. the cut looked new and recent. I was shocked because at the time the care still had warrant. McCarthy Germiston were the only dealership that have worked on my car. I have enquired a number of times with the Workshop Manager and Service Agent in trying to find what happened to my car when I left it with the dealer, they are reluctant to assist me in finding the truth. My car has a damage that I am very much confident that It happened when I brought the car to a dealer and my car came back with damage and faults that I was not made aware of. I kindly request your assistance and intervention on the following: 1. What/who caused a damage on my car? 2. The performance of my car remain the same even after diagnostic and replacement of timing chain. What causes that? car. 3. Please assist me to ensure that my car is sorted. I have sent a complaint to the dealer in March and I could get any response. ?

I'm handing this matter to Hellopeter.com because i trust that you can assist me regarding my car.