Debits 2 months after canceling contract

I had a FreeMe 2Gb contract for two years and was due for an upgrade in August. I called Telkom Mobile on 30 July to let them know that I would not be renewing and would be converting my number to prepaid. This was seemingly resolved.

Now, could someone tell me how come I am still getting debited for the contract I cancelled two months ago! Why is this happening, Telkom?

I demand a refund!