I recently opened an business account with FNB ,

I recently opened an business account with FNB , it has not been 6 months since I opened the account, to open this account I had to pay R50 and since then I haven't deposited any funds on the account, and there has not been any business since all of that is because its not easy to do business these days. and now I'm getting messages that I owe the bank R 990.61. And I getting Lawyers sending me email. is the bank trying to get me blacklisted

I feel this is wrong at all angles , so I'm being punished for not having money. How does one deal with this.