Still unhappy about the service of resolving the issue of unpaid deposit

Thrifty is still lying about refunding me th deposit. Thy referring to amounts that they paid me which one of their staff members even confirmed that it's not my deposit in March when I asked them about why they paying me less. This time they sending me statements that are indicating that I was charged for petrol while I returned both cars with a full tank. They also charging me for kilometers on both cars while I was driving to and from Pretoria everyday and the kilometers were always less than 100 a day (based on the fact that they give 200km free per day. When I asked the person sending me the emails (the name is Shikaar Baijnath) to give me her contact details so that I can explain to her, sh never responded to my email up to date. So I'm still a very unhappy client