Worst mistake of my life

I took my car to the Centurion branch and honestly speaking that's the worst mistake I have ever made. I took my car in at the end of January and R9000 later my car was worst than before and now even leaking oil. I called them back a few days later to inform them that my car was now experiencing issues and I was advised to bring the car in when I get a chance. I was out of town for a month and as soon as I got back I took the car back in. I had taken the car to them for a service and additional repairs hoping to use it for this trip, I couldn't even use it because of how it was performing afterwards. I was accused of having driven the car during that month and of taking it elsewhere for repairs after it was with them. I advised them to check how many kilometers the car had traveled between the time it was given back to me and when I took it back to them, I never got a response from them, they now fixated on accusing me of taking the car somewhere else. Long story short I was forced to pay R450 for the second diagnostic done on the car after I had brought it back by the rude lady who is the receptionist and owner's wife before they could give me my car back. I was told that the car has probably always been leaking oil and we never noticed and that it might be leaking cause they now put in new oil. I was told that the reason my car is now sluggish(which started after I took the car to them) was as a result of a component that broke in the car after degrading over the years. It's funny how it broke after they worked on my car right? Well, I thought so too!