Cannot close Nedbank Credit card.

I fully paid up my Nedbank Credit Card last month. I enquired via the chat on the app how to close the card, I was told to go to a branch. I went to a branch yesterday and I was told the only way I can close the account is via phoning ***but after the initial 'Welcome to Nedbank' pre-recording, the call just cuts.

Now I see Nedbank has changed a ~R300 finance charge, which I believe is interest, on my fully paid credit card. In fact, the card was in the black by a couple hundred rand.

I need someone to contact me with a resolution and an explanation on why I was charged interest on a fully paid up account.