Bad Service of Money Making

I have cancelled my contract on 12 October and request that my number be migrated to prepaid on 12 October 2015 via helpdesk and email and was told it takes 48 hours. I have in the meantime received mail asking why on which I responded. I have now received a full bill for October and will probably get one for November as well, which I will not pay as my request is outstanding for 23 days. I have put in my cancelation not my problem if MTN is too slack to action my request. THIS IS BAD SERVICE. I HAVE SEND SEVERAL EMAILS YESTERDAY AND TALKED TO 808 AND HAD NO FEEDBACK TO DATE.