Avis has debited my account 3 times

<p>I made a car rental with Avis at OR Tambo on 19 May and my bank account was debited with R12000 and R3543.62 same time. I asked the agent at the airport on why 2 amounts especially for the R3543.62 as the reserved amount that was quoted was only R12000. He said it was for security reasons. I returned the car and R1805.32 was also debited from my account on same day as the two transactions which I was informed was the actual charge for rental. They now no longer want to release back the difference of R13738. 32 that they took from my account. I have been calling my bank and avis with no luck.</p>