POOR REPAIRS SERVICE

I have a serious complaint about Hyundai Edenvale. My vehicle Elantra has been at their dealership since beginning of Feb for service & other repairs, as they had given me an eta of 2 to 4 weeks to receive the parts to repair the vehicle after they did the diagnosis. A week from the day I dropped off my vehicle, I received a call from Ayanda saying that the ETA for the parts delivery is the 21st Feb. On the 15th of Feb on a Monday, I got a notification that someone took out the car battery, then I requested for Ayanda to call me back which she did and she then said the vehicle is repaired & ready for collection. I was so surprised that so quickly the parts have suddenly arrived! Had I not contacted hyundai after I received a notification that someone was busy with my vehicle, no one would have called me so it's very surprising. Anyways I told them I would collect the vehicle on Saturday the 19th Feb since I was working & knocking off late. On Saturday I went to the dealer to collect my vehicle. When I got there, my service book was not filled nor stamped to show that they serviced the vehicle. I had to call them to find out why, so they could stamp it. When I started driving the vehicle the engine light emidiately appeared & started flashing. My vehicle sounded terrible as if no repairs were done at all, which I doubt they were done. I had to live my vehicle at hyundai again, I'm even scared of driving it anymore now because I don't trust hyundai edenvale like I used to. I'm angry, stressed & very much not satisfied as they failed terribly to help fix my vehicle. Anything could have happened to me had I driven that vehicle as they claimed to have fixed my vehicle of which they did not fix it at all or they did just not do their job well which is very much ***********. I love hyundai & wanted to upgrade but at this point I doubt I want to have anything to deal with it. now