Closed old cheque account fees pilling up

More than a year ago, I was in and out of hospital advised FNB to close the account I have with them due to my financial situations. I couldn't go to the branch because I was in and out of hospital due to COVID, other banks did close my accounts except FNB, I decided to come back to my surprise I owe FNB?????? Banking fees??? Some say it's a loan, some say banking fees, I don't have loan with FNB

I need FNB to sort out that amount of R6474 because I don't owe FNB. I tried talking to the bankers, the answer I got was (Please contact the Risk Management, Credit and Collections for further assistance *** operating hours M-F 08:00 - 16:30) of which it's what I have been doing for the whole day.

Been sent from pillar to post, of you check on my profile I probably called more than 10 Times today without help. Let me know how you gonna fix this because it looks I have made a huge mistake coming back FNB