It has been a month and I haven't received my deposit back!

I rented a car from them on the 26th of April, I returned their car on the 28th of April. It is now the 20th of May and I still have not received my R4000 deposit back. I have emailed twice, I have called their Lanseria branch twice, first speaking to a guy named Mlungisi who said he would call me back, I never received a call back, the week after I called again and spoke to a guy named Calum who said he would call me back, but never did. Basically this is *****ing, it seems like they take your deposit, they don't pay it back and they do everything they can to avoid paying you back. They have not even made any effort to provide feedback on the situation at all.