Worst service ever and an expensive experience

Took my car for a quality check, they told me there's a minor oil leak (im not sure if there was ever a leak). I said they can go ahead and fix it. They called me to come and fetch the vehicle 3 days later, just as i drove out of their workshop, oil was leaking badly from the engine, i drove back just after a few mitres and they saw the leak and asked that i leave the car so that they can fix it. 2 days later they called me to come to collect the car. Now the oil leak on my vehicle is worse which is staining my driveway. When I called them I was informed by their chief mechanic Kuben that it's the Turbo that is leaking. This diagnosis was made by Kuben without even physically inspecting my vehicle. Now my vehicle drive train light keeps coming on, the engine shakes badly which is going to cost me more money to fix after paying 20k to fix a minor leak. I called the owner directly to tell him about this and he told me to bring the car back. The problem is I'm scared to take my car back there because this Kuben guy who seems to be the main mechanic might course more damage to it.