Unauthorized Debit Orders (Advance PS 106168.....)

I have been using FNB for more than 15 years without a single complain but all of a sudden I see a surge in unauthorized debit orders. The debit order I am complaining about debits R580 from my account since November 2019 and It has been 8 months now totaling R4640. I have tried to use their app and website to dispute or stop the debit order with no success because the debit order is above R200. I went to the nearest FNB branch and they referred me back to the app and gave me an 0800 which also referred me back to the app. I am left with no option but to close my account. I just wonder why FNB is allowing people to take our hard earned money or they are working with them