damage of property and bad management

I had taken my car in for servicing and I was aware that the back ligh had a crack. After picking up my car I noticed the light had been cracked to the extent that the glass had been taken out. I had approached the manager Shane Govender and he was arrogant and refuse to offer me any help. The place is currently under renovation and there is a lot of dust and dirt surrounding the area. The manager looked at the light and had seen some dust inside. He said that looks like old dust that had collected there. My point is that the cars are washed thereafter howcome they didn't wash the dust away? If that is true. So basically the manager gave his theory of what could have happened and refused to help me out How is it possible that a pressure hose could not have removed \ old dust ". That was supposedly inside the light? If the light had just a crack how did the dust get inside the light? I would have understood if something took place mistakly and caused the light to break"