Debited my account without my permission

I had a personal loan with nedbank a few years ago. the account was handed over. I went into the bank in May 2015 and opened a new account for my salary to go in. Nedbank Personal loans debited my account for R451.01 without consulting me. I contacted the personal loan department and they said that they can do this without my permission. I feel like this is unacceptable and the bank did not want to reverse this debit