Poor Service - FNB

Good Day, for the past 5 months i have been struggling with unauthorized transactions on my account, a debit order called Nedcard deducted R16580.00 from my FNB account & it happens every month & every month i must pay fees t have this transaction reversed. What about FNB putting this so called "debit check mandate" in place if anyone can take money from my account. They are quick to sell me something but to resolve my query takes millions of years. I logged this query with them numerous times & i did it again to do which i had to pay R40 for to reverse a transaction i haven't authorized which has been going off for the last couple of months. If i don't get assistance to have this transaction stopped i am taking matters further because my family depends on every sent in my account & here FNB barely cares about it because i am just a number in a book that this is happening too.