Car comes back with new problems every time I take it in

I took my car in for a service and it came back with battery issues. I took it back for them to fix and it came back making a grating sound under the bonnet. The agent I was dealing with, Sisanda, said it was linked to pre-existing issues that, coincidentally, only started manifesting after they returned the car to me. All this while their service cost me R6000, twice as much as the next place I looked at. If you're looking to have repairs done to your car, I'd recommend shopping around. You can have it mangled for way cheaper.