More damages after service

Three weeks back I took my car (Hyundai Atos 2021)for 30000km service it was okay without any issues. When I take it in the afternoon the job card was having an issue of leaking radiator, i took it as I knew that it is drivable. When I was driving home i noticed that the oil is leaking and some smoke was coming out of the bonnet, I stop by the garage to check only to find out there was no oil left in the engen, I bought 3 cans of oil and put it, when I arrive home I asked the mechanic to check it for me. He checked it and take out a piece of rubber that was inside, he said it was the cause of all this issue, when they change the oil during service they left that rubber after that the car went back to normal. The following day I took the car back to this dealer to inform them the issue I came across, they acknowledged their mistake, apologised and refunded me the money i used to put some oil , they asked me to leave the car so they will inspect if there are no worse damages that occurred while I was driving it without oil and I left it, in the afternoon I collected my car, on my way home it starked on the freeway which I called them again and report the issue, they said I must share them my location which I did. After some minutes they told me to call hyundai roadside assistance which I did, they towed the car to Hyundai the Glen. After two days Hyundai the Glen told me that car has a problem of engen, I told them to communicate with Hyundai Sandton as they know everything about the car but Hyundai Sandton said they are not responsible for any damages and fixing the car and any payments needed for towing. I had to take my car as it was on another dealer which I didnt know that they are not working together. My car is on stationery right now because i am still making some means to solve the issue. I am very disappointed and hurt as i loved their cars but the experience i got is very very painful. I dont advise anyone to buy Hyundai cars as also the gears are problematic and while i was there complaining i overheard other customers having a complain also after servicing their car there. If I have power I would advise that they close this branch (Hyundai Sandton Kramerville)