Worst service ever.

Hertz is holding my Deposit of R13000. They issued me two invoice already which shows I don't owe them. I have called them one of the agent was rude and cheeky. Sent my query to customer relations on 20 Feb, acknowledge of receipt was sent back, however no response yet. Sent compliant on thier Facebook wall page. Got on response that says they are investigating the matter and they will call me back. No responses till to date.