********** Debit Orders

I thought FNB already dealt with ********** debit orders. I have a debit order of R5000 that I don't know and never authorized. I don't understand why I can't reverse it on the app and why I'm charged reversal fees for something I never authorized and why I can't get the money back immediately. FNB I need this money for my legitimate debit orders and I need it ASAP. Thus obviously is not my fault, I can account for debit orders that I have authorized.