Money out of my account without permission

More than R 86 000 was reserved for purchases out of my account at FNB. I had to report it, fill in many forms, argue with the bank make hundred calls and wait days to sort out the problem. Luckily the problem was solved. One day after this FNB took R 70 000 out of my account without paperwork, messages, investigation calls or anything. They just send me a sms saying that my account is in excess (R 70 000) kindly adjust. I don't have overdraft facilities, I did not apply for any, I don't want this. who in the hell does this bank think they are. This is against the NCR 's rules.