Account Was not closed, and was still charged

Hi, I have just received an invoice for August from you charging me for a Telkom Telephone Account which I no longer have because I physically went into the Telkom branch in East London last month (July) and had it closed. I have been waiting a month for you to send me the final settlement Invoice email, which I have still not received, but instead got charged for August.. please could you explain to me why my account has not been closed?! as I have immigrated to the UK and am no longer in the country to even use the service. I would like my account to be closed please, and for you to send me the correct settlement amount I need to pay. Thanks.