Contract cancelled yet they continue to bill me

We cancelled our contract which expired on 24 October. We gave a months written notice and were advised to call on Monday 26 October advise them to move the number to prepaid as we do not want to to continue our contract due to the terrible service MTN has given us. We called<br> 808 and they confirmed the number would be moved to prepaid however week later and I have called 808 to confirm and the number has not been moved to prepaid.. Further problem is they appear to have doubled the amount I owe again. Monday 26th 808 confirmed I owed R700 minus the discount. Now I apparently owe double that is. R1500. MTN must please send me detailed billing of how they claim to have reached these amount that they have billed me. I find their system to be ******* and inaccurate. I will not be paying for any charges between 24 and 1 Nov as they have failed to move the number to prepaid.