Telkom keeps billing me for cancelled lines

On 23 October 2018 I cancelled 2 Telkom lines and received e-mail confirmations of the cancellations. I even received a phonecall from a Telkom guy confirming the cancellation. It is now 5-month later and Telkom is still billing me for these lines. Every month I phone Telkom who confirms that the lines has been cancelled and promise to escalate the matter to the Cancellations Department. I am still being billed for these lines. I can't stop paying or pay less, because I have other lines as well. If I stop paying or pay less, they cut my other lines.

I hope Telkom picks-up on this simple matter and resolve it asap.