Gas cap and door left opened.

This morning I went to Sasol Chloorkop to put in petrol after paying I drove off, on my way out I heard funny noises I stopped my car to check what was happening, I found the door and the petrol (gas) cap opened, So the tenant left my gas cap and the door opened. I understand the station gets busy but atleast check some things, which could be hazardous. When I tried to call their number that appears on their slip line does not work.