Avis are ******** when it comes to returning deposit

When we picked up the car they took a R2500 deposit, they said the money would be kept on hold and released when the car comes back undamaged. When we returned the car they said the deposit wil take up to 30 days to reflectback in our account. We returned the car the 4th of August but the deposi money has not returned to our account. I have called them 5 times now and the customer care personnel is useless, firts they said the money has been released from the hold, but it has not, when i told them it definitely hasn't they tell you to hang on while they check every time then the call just end after about 8 to 10mins of waiting. This is so unacceptable from such a "big company". If the payment has been released like they claim we want some tipe of document proof stating as becuase it sure as hell doesn't look released.