Incorrect account dedbited

My debit came off this morning from my old nedbank account which I have not been using for over 2 years. When I called this morning to query this I was told by customer care that they only have my FNB account details but they will contact accounts to confirm what account was debited. Accounts then confirmed that the only details they have is my nedbank details and that it was changed on the 5th April. I have no knowledge of this and what's very concerning to me is that this is completely unauthorized. Who gave you guys any authority to debit another account? It did not come from me. To top this off I am now gonna be charged for an unpaid debit as there is no funds in that account because I don't use it. I want a manager to contact me regarding this because this is *****.