Harrassment from Nedbank

I had an account with Nedbank, which I was not using. Nedbank informed me that they were suspending the account, for that reason and that I could contact the branch when I was ready to use the account again, which I accepted. When I discovered that this suspended account was attracting bank charges, I opted to close the account in writing and got a response from Nedbank stating that the account was now closed, on 17 July 2015. Since then I've received a statement indicating that the account now has an overdue balance of R93.16, which I paid into the account, assuming that that was that. Not so! The amount was returned since the account was closed. I received an email stating that I needed to pay this amount or the matter will be referred to their legal department for collection, which I ignored. Today I got an sms stating that \an urgent payment of R40"was required"