Autopage forfieted my airtime

i called up in January to cancel my Phone contract. the lady i spoke to advised me that it will cancelled as of the 17/02/15 to which i agreed. on the 13/02/15 i recieved an SMS stating that i am now on MTN per second billing. when i checked my balance i had just R10 airtime compared to the -R300 i had the night before. i called up and advised that this has happened and my response was that when i agreed to move over to pre paid any balance i have will be forfeited. when i advised then that i was told it will be migrated on the 17/02/15 and not the 13/02/15. i was then pushed to retentions at which time i was cut off when i asked to speak to manager. i called up again and spoke to another agent explaining th situation and then spoke to his manager. i have still not heard feedback from them. i then tried to call this morning where i was on hold for a hour and the the line went dead. all i ever wanted was all my airtime data and sms's to be refunded to me but now that this is not being sorted i might as well cancel my debit order for the last payment which is more then what was taken initinally