can you please cancel my contract

I have been liaising with MTN since lat August this regarding the cancellation of my contract. My two year has expired and I wish to discontinue my contract. but for some reason MTN's cancellation department is not interested in completing my request . I have sent an email in email in September and I have made several calls to your contact center since August . this is just unacceptable can someone please complete my request urgently as i am now unable to buy airtime or data bundles because i was advised that i would loose these once my no. has been converted to prepaid. i am very disappointed with the lack of service from mtn.<br>