45k service that has damaged my car.

Firstly I'd like to thank you for your part in my experience with Hyundai both you and Leon the sale consultant who had sold the car to me have been very professional. However I write because I'm upset and to be honest unhappy with the service on my car. From the time I brought my car for its 45k service I have had issues. When I brought the car in on the 12 September 2018 at 7:40am the car had no issues and my only reason for bringing it in was because I was told that I had to bring it in for its 45k service. My car had never given me any problems. Yes I have scratches and a dent on it but my mechanics in it have always been in good condition just as I had received it in March 2017. However since the 45k service with Hyundai umhlanga my car was giving off white smoke in the rear end with a smell , it had been jerking on the road while driving. So I brought in on the 11 of October 2018 . I was assured that the handbrake had been binding which was sorted ,everything seemed to be perfect until today where the car literally switched off 4 times today while I was driving. Why would a car which had been again fully inspected and serviced start doing that after I was assured everything is fine after the previous issues picked have been resolved? I don't care however long it stays with you guys I would like my car to be fixed, properly at that matter. I can't be living in fear every time I'm on the road of what will happen next. My tummy is literally in knots when I have to drive to and from work cause I don't know what will happen next.