Contract never cancelled upon request - now bad debt!

<p>I cancelled my contract with MTN on 28 Apr 2016, I called in to do so, they advised as not to lose my number that I should convert it to prepaid, I said yes. Ref no: ********** 85, This weekend I receive a call stating that I owe MTN money.... for what? I followed up on this and was assisted by Ronnie Chetty in the call centre Ref no: ********** 3 and he notified me that the request to covert my number to prepaid was never actioned and therefore the account had accrued charges. This is not my problem, I cannot be held liable for money on a service I did not use or requested to be cancelled and was never done. I need this matter resolved as it has now affected my credit rating and I have been denied a contract upon application elsewhere! I want somebody to reverse those charges, close the account once and for all, s**** that number completely from my name and clear my credit record! I have tried calling the call center which Ronnie advised me to do and they answer but just never speak to me, so how am I supposed to get this matter resolved.</p>