Debit my cheque account with my authority

Dear Sir/Madam<br> <br> I am very disappointed with ABSA, I am Platinum holder I have Cheque Account , Credit Card,Vehicle Finance, Investment and my Will with Absa. They just disapointed me and I m thinking of moving all my account to other bank.<br> <br> In November last I used my credit to purchase goods , but available balance remained constantly, I phoned credit card division to report the metter, they said I must not worry there is nothing wrong with my card I must continue use my card, the following day when I checked account balance it shows that my I over withdrawn and inalso received massage from absa and call. They told me that my acount was over drawn but I told them it was their system wich was delaying to update account accordingly , they asked me to pay shortfall immediately,but I told them I can only pay aR500 per month. Since than I have been paying as per our agreement , but today ABSA withdraw R1600 in my Cheque account to Cr Card without my authority, I feel this is not fair, they are taking the advantage that I bank with them, how they withdraw so much of money?how am I going to surviave for the whole month. Please help me to get my R1600 back. I