Debits with no permission and no feedback, Bad customer service

Nedbank has debited my account 6 times in two day for my greenback account, when querying this with the call center I was told that my account was not debited for 6 months and that is the reason why I got it debited all at once. I did not get any notification that this is going to happen. When checking my account on the money app i find this out. This is extremely bad service as i was not informed and had to call the call center to assist and get a supervisor to call me back, to date i have not received a call and i spent more than 18 minutes and got no resolution.