Unable to close an account

I have made numerous attempts to close a business *** that I never required but to no avail! I received a letter of demand and a number to call for queries. After speaking to 4 agents I'm told that I can't be assisted as they are just a call center. Why put the number for queries when they can't help? The 4th agent tells me to visit a branch which I do a few days later and they can't help either and I'm told that I have to visit the branch that opened the account and FNB will continue to charge me bank charges until I deposit the money for bank charges. The problem is that I'm currently unemployed and I've made attempts to ensure that the account is closed and no more charges are added but no one can assist. I am unable to visit the branch that opened the account due to me being unemployed. I've just received another statement and another month charges are added! I really am out of options as no one from FNB is able to assist in a simple account closure