Poor workmanship, dishonesty, wrong diagnostics and failure to account

Hello, I took my car for major service at car care clinic Boksburg. They called me to tell me they did the service and the car needs engen flush, radiator flush and the break fluid flush, I told them it's fine they can carry on at an extra cost. Later on I called to check if the car is ready and fine. They said yes it is they were about to call me. The manager told me I'm happy with your car we tested everything is fine and 100℅. I drove the car and it was ****ging and loosing power. Then I noticed the smoke coming from the car bonnet and the oil smell. I then pulled over only to find that one pipe was broken and oil splashing all over the engen. I called them and took the car back. They changed the pipe with a different one which is not the manufacturer's one that came with the car and told me those pipes has that problem and the one they fitted is strong and it won't give issues. The car started vibrating worse and switch off by itself. My 1st time seeing an automatic car cutting off by itself while driving. They did their diagnostics and told me no faults found. While they were busy doing the test the manager told the technician to check the spark plugs, only to find that the plugs were not changed. They changed the plugs and it didn't solve the problem.Which makes me wonder if the service was really done. We then drove the car to one of their friends to check the car further. The guy told them that the problem comes from the breather where the changed pipe is connected. He said the car is struggling to breath thefore it pushes the air back to the engen and he proved that by removing the oil cap on top of the engen and the car was smoking and breathing through the cap. They did the compression test and told me one cylinder has a very low compression, now I must change the rings and it will be at my cost. When I took my car for service 1st it didn't have any of those problems. I took the car to them about 4 times with the same problem and they kept ignoring my calls and every time I get hold of them I'm told a different stories with no solution. Why was this not picked up when they were doing their full 76 point check? All of a sudden I must change the rings that's why the car is vibrating so bad and cuts off by itself.