FNB Bank charges changed to a loan

A few years ago I opened an FNB account and never got to use it, I then emailed FNB for account closure to inform them that I had opened it and needed to close it down before I was charged, no feedback was received, a year later, I owed them R6000 off charges from an account I've never even used and had asked to be closed down, now it's 4 years later, that account has been closed and that owed amount switched to a personal loan and showing on my credit. This is not only ********* but really frustrating and annoying cause I won't pay for something I'd asked to be closed and would be a fool to do such, next steps, I'll be taking the legal route to get them to rectify their error and clear the amount owed, this is possibly the worst banking experience I've ever experienced. Something needs to be done with how FNB operates and treat their clients.