FINE - NO OVERDRAFT

Unfortunately, an incorrect debit order went off my account and I was given a fine of R90 due to the fact that there was insufficient funds. My question now is, I did not ask for any overdraft or given permission for an overdraft on my account, so how can Nedbank allow any payment to go off if there are no sufficient funds? It was not due to my mistake or reckless management of my funds, however, I am now liable for the fine. I find this very unfair to make me the responsible party as I did not give permission for this to happen to my account. If you do not have the funds, they cannot let anybody take money from your account. The debit order should have been returned with a note of insufficient funds.