Frustrating cancellation experience

A bit before I emigrated from South Africa, I called MTN to cancel my contract. I was told that the cancellations department was offline (I think the term they used was "uncontactable due to technical difficulties"), and that I should call back the next day. I pointed out that I am leaving the country and that I can't do that, to which they suggested I send an email to customer care and retentions requesting this. I did this and got an auto-response saying that they will get back to me within 24hrs. It's been 3 weeks since then and haven't heard a peep, but I have still been charged for the new month's which should have been cancelled.

Reference number: fef7d8c6-87e5-4b6e-bca5-a99b8621c73d