Very disappointing

This people take chances, they were suppose to fix our car which mixed oil and water due to apparently a side gasket but was still driving fine, they were suppose to fix this and go through the whole car to make sure everything is perfect. They had the car for more then 2 months and still was not done, eventually after all this time we could go fetch the car which clearly was not finished still as they were still busy when my husband went to fetch it. Taking the car home from their shop we literally drove about 3km and the motor made a noise and was just oil and smoke everywhere, a valve dropped and broke the piston and everything this after they overhauled the motor and did engineering on everything or that is what they charged for but clearly was not done correctly, now with all this damage they don't want to take responsibility and are saying we broke the car, how is that even possible?? I am so disappointed in this place as I now had to go fetch the car completely broken after he was paid more then R10 000 just to have a car that is now more broken then before they had it... They clearly didn't do what they were supposed to if they even did anything.