Deducting unauthorized money from my account

Avis South Africa - Soweto Branch. I used car rental from Avis through the insurance. I had to sign a form indicating that if anything happens to the car the access would be 2416.xx. Which I signed next to. The gate closed in on the car and I informed Avis about it. On Monday 29/06/2015 they contacted me and asked if they can deduct the full access amount. I asked what about the 1200 deposit I already paid. They informed me that the money R1200 will be paid back to me in the week. On Friday the 2nd of July 2015 I still did not get the 1200 back. When I phoned I was informed that with a cheque card it takes some time. On Monday the 6th of July instead of avis paying back my 1200 they deducted an additional amount of 3480.16 When I phoned avis to ask what is going on they indicated that it is the full amount of the damage. They currently sit with R6833.95 of mine. The form I signed said access is R2416.xx not 6833.95. in any case this can't be full damage either as I got a quotation that the total damage is R2505.00<br> According to me this is *****, deducting money from a persons account without any authorization. I will be opening a case at the police station if this is not sorted.