Nedbank EFT errors

Their NRR *******ly debited my account without my permission. they apparently duplicated the eft that I did to my standard bank loan account. They then requested me to refund Nedbank. I then requested proof that the money was duplicated and they could not assist. They started harassing me and threatening me with the Sheriffs visits and SMS's. I took an initiative to call them (and they can listen to their recordings if their calls are truly recorded) and stated clearly to pay back the money if proof is emailed to me, I spoke to Reshma she was so rude to me and I even threatened to close my account if they will carry on talking to me like I stole their money and yet the error was on their side, she told me to do as I please she is not bothered. I have listed the names of the agents I spoke to and date and time of calls. The last person I spoke to was Anesu(Team leader) who was so insensitive and laughed at me when I told him that I have serious financial problems and cannot afford to have them debiting my account anytime they feel like as there should be an agreement between myself and them. He promised to revert. He never did. All my calls to them lasted more than 30 minutes. My account was debited on the 21 August, I then called Nedbank to reverse payment as I was not sure who debited my account at that time and was told they cannot as it was one of their divisions and was transferred to them. Another debit was done again today whilst I am still waiting for their email and I tried calling Anesu as he gave me his direct line and the phone is continuously ringing. I feel I need to close my account with them as they do not care about their customers.