MISSION TO CANCELL CONTRACT

I called the contact centre (808) about a month ago to cancell my contract,they told me they are experiencing high call volumes and that someone will call me back withing 48 hours (***).No body called me back & now I cant call the cancellations department because my contract expired.Apparently you can only call them with a contract number.Last week Friday (2015/02/06),I called the contact centre to find out if my contract has been cancelled and they told me they cant put me through to the cancellations department as my number is on prepaid.Now I dont know what to do because at mtn walk-in stores they told me to call 808 & I'm not getting any help.I dont want to be billed & I dont want to be credited with data.