Illigally enriching themselves with my security deposit

This car rental business refuses to refund my holding deposit despite numerous calls I made, they have no answer. The rental was for 2 days, I returned the car on time, with full tank and no damage whatsoever. One agent says security is released after 7 days, then the another says 14 days. It has become a norm to be ****med in Sotuh Africa. And what do I get in return, absolute contempt.