Cancelling MTN contract

On the 19 October 2015 my contract with MTN expired. I call MTN notifying them that I'm no longer interested or renewing my contract, however I'll like to migrate to prepaid phone using the same contact number. MTN promise to send my request to retentions then retentions will send me email confirming my request.<br> Today I receive air time from MTN that means now MTN imposing their contract on me.<br> Please Hello Peter assist you are my last hope. <br> My Cell phone number: *** <br> 1st reference no: 136 717 493 <br> 2nd reference no: 136 794 677<br> 3rd reference no: 137 091 834<br> Retentions Reference no: ***9, ***5 the person name Simphiwe Thwala from MTN Retenstions<br>