Deposit being held hostage

I hired a car and for R69 they are holding my deposit worth over R11 000. I have called the Head Office, I have called the call center, I have called the branch and spoke to Mac Joseph. Not one person can tell me why my deposit is being held hostage, earning interest in their bank account for R69. No one can tell me when my refund will be taking place. I have been given the Branch Managers number, Paula Bryce needs to learn how to be a Branch Manager and answer calls or at the very least return calls. What pathetic service and I cannot escalate to one senior person! Why are they so illusive?