Fnb can't help reverse a debi check debt order

I think fnb should do better because this os unacceptable I am trying to reverse a debit order and i'm told because of the debi check I can't yet i did make sure the mandate has been suspended fnb this unacceptable and no one is helpful at all there should be a option to reverse Debi check debt orders this has left me disappointed that I don't wanna be with fnb anymore