Closed credit card handed over to lawyers?

I Closed my standard bank credit card in Sept 2015,only too receive massages 6 months later to advise I'm in arrears. I then contacted client services immediately to query this, they advised it was a Standard Bank life insurance that was stil debit on the Closed account?. My first question was, howcome no-one contacted me the 1st month, as how was I too know about any transactions on this account if it was closed?. It could have prevented the insurance from having interaction on this account. Noting that all insurance was cancelled upon closure hence I could not understand why it would stil debit?. Told that the cnsultant that assisted me upon closure did not action the cancellation. who's fault is this..as the consumer I am being threatened with lawyers? Liaising with the call centre for the past 3 weeks i stil have no joy to obtain the recorded call in September when I closed the account. This is effecting me negatively as the consumer as I am in breach of a bad credit record and its not my fault.. How can any interaction occur on a closed account anyway? What credit facility's are available to do so? Does closing your account not mean that all credit is no longer available? Therefore how was this insurancer paid ?...