Fnb is the biggest rip-of taking people's hard earned money for no reason

Fnd is a rip of , I have opened an account with them but haven't used it for any transactions I didn't have the time to close it because I work 7 days a week and I have to go to a branch to close it , I have now received a bill on R850 bank fees when I have never used it not even once this is total ******* and unacceptable. I have dealt with nedbank many years and not once had an issues I once.never used the nedbank account for many months but never received a bill for not using the account. I dont no how to deal with fnd this is unacceptable and im in no position to pay that money for no reason. How can a bank charge R850 bank fees for an account that has never been used.