FNB closed account

In 2017 my (now) ex husband went under debt counselling. The debt counsellor could not pick up any debt under my name so the court documents was only under y ex husbands name. After our divorce I submitted my divorce degree to the NCR for removing my name from debt counselling. About 6 or 7 months later I needed to buy a vehicle because my ex husband sold mine. I could not get finance because off outstanding debt at FNB. I contacted them and asked what this outstanding debt this was because there was nothing when I went under debt counselling. The Call centre informed me that it was for bank fees. I was blown away because I did not use the account for over a year. According to my knowledge the bank close the account if you don't use it. And nothing showed on the ITC profile. I tried closing the account but FNB refused. Said I needed to pay the 6500.00. FNB never sued me but listed me on ITC. Why must I pay for an account that hasn't been used since 2014. Please I need to buy a vehicle because my ex husband sold mine. I am a single mom. I don't have the money to Pay FNB for nothing.