Never take your car to KIA Motor Alberton for service. My car has a problem it never had after being serviced at Kia Motor Alberton

I took my car in for service at KIA Motor Alberton, in August 2020. After the service, the service department usually leaves all the parts that were removed from the service, in a plastic bag in the car. In the plastic bag I realized bits and pieces of hard plastic and I though it must be from the service and since its in the plastic along with other parts to be thrown away, it was not important, so as it is normal I threw the plastic bag away when I got home. Recently I opened the boot to charge my car battery and I realized that the air filter box had a hole in it, and was also loose and not clipped on, there were was none. I quickly remembered that the bits and pieces of hard plastic I found after the service in the plastic bag were broken pieces from the air filter box. So I went back to KIA Motor Alberton to ask that they replace the air filter box since they broke it and were the last people to touch the air filter box during their service on my car. And to no surprise I was treated badly, I was told that they (KIA Motor Alberton) are not liable and will never replace or fix the Air filter box and I was even asked to leave. I am not happy, KIA Motor Alberton refuses to fix the box they broke. I need help to get KIA Motor Alberton to fix their mistake.