FNB DESTROYING MY REPUTATION!!!

I am so disappointed with the treatment I have received from Nedbank. About a year ago I opened an account and wasn't informed that in order for the account to remain opened I had to deposit a minimum of R30k per month, failure to do so would result in consistent ridiculous banking fees. Had I known, I wouldn't have opted for this. Once I wasn't able to deposit this amount into the account, FNB continued to charging me fees for not depositing into the account. I never got any communication from them, not via phone or email, a year later, I have just received a TEXT MESSAGE saying I owe the bank R5 995.53 and that my name has been given to the credit bureau. When I rang, I was told the case is now with CBS Legal DDA and I should deal with them directly. I tried calling, and requested a call back... Nothing so far, yet each month I'm being charged an interest fee on an account no longer exists for a service that I do not use. How is this fair FNB?