FNB Debit Orders

There have been debit orders of R659 going out of my account since September last year, and I couldn't dispute the debit orders, so I went to the branch and told them to help me cancel the debit order and refund me all the money that went out of my account because I never authorized any debit orders, nor did FNB send through a request for me to authorize as a security measure like they normally do with all the debit orders that go through my account, but they said they'll only be able to refund last month's debit order, not more than that. And on top of that, they charge for the cancellation and refund of debit orders. As a customer, I really thought they'd be able to give me a refund of all the months the debit order went out, but unfortunately they couldn't. I'm highly disappointed by their services. So far I have lost R6590 over 10 months, plus R100 for cancellation and refund of something that was not even my fault; I only got R659.