Unauthorized Debit Order

I have been with Nedbank for a couple of years now, and recently they are charging me R10 for the debit order I know nothing of (MDS M/C IN 1********** INS FUNDS). I have tried to talk to their agents online, but they keep saying that R10 is for insufficient fee amount. I have never authorized any debit order from my account and they can't even explain what is happening as their client. I might as well close my account as they are playing games with my money.