Incorrect account credited

On Saturday, 25 July 2015 I went to the Telkom shop at The Bridge shopping centre in Port Elizabeth to pay my account. I used my debit card to make the payment. Whilst helping me the consultant was also.processing payments from other consultants. I made sure that my account was paid in full. Today, Thursday 06 August 2015 I received a text message from Telkom wherein they claimed that my account was not paid. Tbey threatened to suspend my service if payment was not made within 48 hours. I called them and insisted that my account was indeed paid. The lady on the line requested me to email them a copy of my receipt. I told her that I refuse to do that as it is their problem to sort out. Why should I help them to sort out the incompetence of their staff. It is obvious that their consultant processed my payment incorrectly. I have a receipt and my bank statement also shows the payment to Telkom. Your staff are *********** and now you expect me to sort out your problem. I do not take kindly to receiving threatening text messages when your staff members are clearly at fault.