Not happy with the way telkom is operating

<p>Good day ,I have a serious problem with telkom,My data contract expired in August this year,app**** to cancel it on the 05 Sep and on the 15th Sep I received an email from them that my contract is cancelled,..to my surprice today 07 October 2016 I received an invoice from them that i am owing them,what must i do to stop this madness</p>