Holding deposit nonrefund

I hire a car and returned it on the 16 March as per agreement. I have tried numerous times to get the holding deposit with no luck. Today is 22 working days but no response on my email. I have called serveral times with no luck I was told the refund department is not taking calls that was on the 26 March. I sent emails as advised but till today no response. I'm worried that I might not get my R9500 refund. I will never ever go back there or refer anyone to them.