cancellation of my contract and not responding

Mtn has very bad service.<br> On the 16/04/15 I cancel my contract with mtn was told it wll be done within 3 days and my sim card will change to Prepaid but nothing was done. When I call again on the 21/04 lady told me that whoever help me didn't send email so she will do that and that consultant will call me to confirm. Still today I am still waiting and worse they send me airtime and I don't want to use it told them to take it back . I also can't recharge because when cancelation is done they will take everything on my phone. Today I tried to call them the whole day but the phone keeps on dropping . I am really fedup with MTN so my phone now its only for receiving. Please post this on their complain never had this bad service in my life