FNB Account

I was a FNB customer for years,moved to another bank and decided to come back.They say I have an account that is still open after years of not using it and I went to the Adderly street branch to close that account.Ever since I've heard about this I've been trying to solve it with no luck.Its still accumulating interest to date.I need help.Calls ,emails and branch cannot assist me.Please help!!!!