Unable to cancel Telkom fibre

On 5 November 2018 I sent an email to Telkom with an attached Consumer Request for Contract and Service Cancellation. I received no confirmation, and the service has not been cancelled. I have also spent hours on the phone with Telkom's customer support team, and despite many empty promises, I have been unable to achieve the cancellation. I switched to a new service provider in December 2018. Telkom still bills me R1107-79 each month, and I still pay them each month, as I am sure that they will react instantly if I stop paying, and I want to avoid being blacklisted.