Utterly poor services

My car was booked last year, 15 December 2023. I had to wait 3 - 4 months before they even started analyze what the problem could be on my car. After these months and waiting, being extremely patient, I finally got my car back on the 4th of April 2024, with several calls and emails from my side, to follow up on updates, due to their poor communication. One of their seniors drove my car for about 200km, whereafter she found no faults. I drove it for a few days and found that there was something wrong with the idling of the car and at times it had no power. When I took it back, they told me that the problem was the catalyst converter, which caused the car to idle incorrect and no power, according to Bosch. So I removed the catalyst as they advised met to do, whereafter the same problems occurred, but this time the car overheated severely and the it had even less power. I took the car back on the 22nd of April, where they found that the head was cracked, according to the receptionist. After a week's time, I still haven't received my car back, nor any solutions to the problems. They are extremely slow to complete their work, and if they complete it, it is not even done properly and correct. This has cost me several thousand rands, due to me not having a car to drive with during the period they had my car.