Broke my wheelnut

Took my car to Hyundai Midrand for a service, and they needed to change my rear brake pads. After I collected my car I noticed one of the wheelnuts was broken off two days later. I immediately took it back and the lady at reception insisted that it was broken when the car came in according to her report. After much complaining I spoke to the foreman who said he broke the bolt as it was not correctly fitted the first time and they werent going to fix it. They instead gave me a nut as a consolation prize, they also mentioned that they did not have any stock of the bolt that was broken. After this I went to supa quick who told me that Hyundai were the only people I can buy the bolt from, he called the same Hyundai and they had stock, from whom I went back to buy it from.I then had to take it back to super quick to fix it. This was Hyundai's fault and they should have fixed it. Very Displeased