Nedbank ********* behavior

Query is ********* behaviour of Nedbank , their call centre ref number ********** (Sehesh) The complaint is the removal of money from my account without my consent, amount R950.0 on the 30.8.18 I called the Nedbank call centre on the 10.8.18 , attended to by Sehesh He explained that that the withdrawal from my account (R950 on 30.8.18) was because that when i had made a withdrawal from Nedbank ATM on the 23.8.18 , i was paid an excess amount of R950.00.This is not true , i would have noticed that.Even if this was true , would it not be ethical of the bank to call me regards this to make the arrangement to repay the money ?Just because they have a mandate on my accoount does not give them the right to do this without my permission and i consider this to be theft. The agent promised to get a Supervisor to call me , to date nothing has happened . How many other people have been affected in this way . Not happy with the way Nedbank treats its clients over 25years