Telkom refuses to cancel month-to-month contract

Since 3 January I've been trying to cancel a month-to-month contract. I have spent many hours calling Telkom's call centre and even complained on Twitter. So far I've resubmitted by request 3 times, and also sent two copies to their social media team.

Cancellation is supposed to take 21 days. However, they never, ever confirm receipt of the email, so that you know they are processing the request.