Failure to close account

I closed my nedbank account many years ago (2010/2011) in which they only notified me in last year that the account is still running. I'm now kept responsible for the outstanding bank charges of over a R1000 that has accumulated over the years which is not my fault. I went back to the bank in which they advised me that it will be investigated but now I'm receiving letters saying that I have been handed over. If the bank failed to close my account that time, why am I only being notified 4 years later saying that the account is still active.<br>