No longer an MTN client, but still being billed!

After choosing not to renew my MTN contract (the reasons for which can also be found on HelloPeter), I then converted my contract sim card to prepaid two weeks ago, as the contract period had expired. Note that the conversion to prepaid was done before I received any of the contract data or airtime for the month of March, and hence was told that I would not be billed my monthly fee of R249.<br> <br> I have since ported my MTN contract sim to Telkom Mobile on a new contract. This morning to my surprise, however, I receievd a notification that a debit order of R294 had gone out to MTN.<br> <br> Please can someone from MTN explain what this debit order was for? I no longer have any form of contract with MTN whatsoever, so this perplexes and annoys me.