Terrible service from Nedbank

I had a debit order in March that went off my account that I didn’t authorise, an amount of R2500. I went to a branch in Katlehong Hlahatsi and the debit order was reversed back into my account and they told me it would never debit again from my account, however the same debit order debited from my account but this time I’m told they can’t dispute it. I’ve been taken from pillar to post now one is willing to assist me, how can my bank let people just take money from my account without my knowledge. R2500 might be nothing to them but to me it’s a lot. I HAVE COMPLETELY LOST MY TRUST IN NEDBANK. This is not the service I had expected from them.