Unauthorised debit orders

Every month I have to go through the pain of reversing debit orders that I have not authorised. This month alone there have been 5 to the tune of R502.98!!! As if that's not enough, Nedbank charges me R5 per debit order to reverse and R20 per debit order to stop the payment. This is totally unacceptable. Surely by now they should have an alert for debit orders under R100, especially ones for R99.99, R99 or any such variations and either not process or at least confirm with account holders before processing!!! Guess that's just too much to ask