They use my vehicle for their own perpose.

I left my vehicle with JHB Executive Parking on my way to Port Elisabeth. I filled my car up with diesel and once i have reached OR Tambo i zeroed my trip meter. After a week when I got back they were not on time delivering my Mercedes Benz ML350. I had to first phone them and wait for a half an hour before they arrived. After they left I got into my Vehicle and found my trip showing 240km on the trip meter and my tank was now only three qaurters full where as I have left it with a full tank. Also they have been smoking in my Vehicle. It smells as if the person who had used my car was smoking with closed windows and the A/C fully on. I then tried to get hold of the company owner over the phone about this problem. They just kept on saying that she is not available. Until now I had no respond from them and it seems they refuse to look in to the matter.