Deposit not returned

I rented a vehicle from Avis on 17 June and a deposit and rental amount was frozen. I extended the vehicle three more times and again amounts were frozen. These were supposed to be released back into my account upon return of the vehicle and necessary deductions were made.<br> <br> I called the call centre and was told that the funds were realized however my bank does not have record of this. Furthermore Avis says they can not give me record that amounts were frozen so I can take it up with my bank.<br> <br> Not impressed!