Call Centre agent calls customer dumb

I received an SMS saying I was in arrears after I have paid more than my invoice amount. I called the call centre and spoke to Tevin to sort this out he then wanted to put me back on hold and I said no due to the fact that I did not want to listen to that horrible music again. he then forgot to mute the call so I could hear the conversation he was having with a women; were I heard him call me dumb where the women said \ you know why she is acting like this\" and Tevins response was \"she is dumb\". <br> <br> I then spoke to Levi who is the manager where the billing was sorted out, as it is an error on Telkoms side and not due to non-payment from my side as I had paid more than my invoice amount ( well I hope it is