Telkom not cancelling account after numerous requests for 8 months

We initially accepted a contract of 2 years with Telkom for a Hauwei WiFi Router. After poor reception and WiFi only working for 6 months of the 2 years we send a cancellation letter as per Telkom's Service Cancellation policy. NOTE : This letter was send on the 6th of December 2016! Since then, we are billed monthly for this "service" without any communication from Telkom. Is it not policy to follow up upon a contract ending to either contact the customer to extend the contract or to cancel??? Anyway, phoning and phoning Telkom, the service provider can't assist, I have to phone this number. When I do, "no, this is not the correct number, dont know why they said you should phone this number. Phone this number..." Ater again wasting my time, "When did you send this letter? Please send it again to ......" Nothing was done. Again I phone and phone and phone and e-mail and e-mail and e-mail.... I WANT TO BE REFUNDED. Currently is more than 8 months just to sort this mess out? Its ridiculous ! This must be the WORST service ever...