Mechanical failure few minutes after the service

I took my car for service at Car city service CBD Pretoria for 105000 minor service on 19 March 2018 , to my surprise when I collected the car few minutes later it had an Engine indicator on and I immediately called the workshop that I will bring the car the following day, after I took my car back still it was not resolved for three times returning the car,

After the engine light disappeared the coolant sign came up on the dashboard and I took the car to workshop again for the fourth time , all this only happen after the service how coincidence, I had to take my car to Audi dealer where the problem was sorted never again to take my car to that place