Not refunding my refundable deposit.

I have been waiting 3weeks for my "refundable deposit" for a car rented at Cape Town International Airport. They told me it will reflect on in my account within 3-7 days, but still nothing after three weeks. When I called them last week they said that the money was released, but they have problems with the banks. The lady said she will put my name on the "urgent list" to escalate the refund. Now when I try to call them, the phone number either does not work, or when trying some of the other numbers, no one answers the phone. The is the poorest service I have ever received from any car rental company. I will never use them again.