Upgrading me without my permission or my concern

On monday the 19th i called MTN call center to let them end my contract with them as this month was the last month for paying my contract that i took in October 2013. i told them i don't want an upgrade and i want to be on prepaid using the same number.<br> on thursday i was trying to check my balance where i found that i have R950 airtime of which i didn't understand because i've cancelled the contract.<br> <br> i called the customer center on Friday, consultant then told me that i took an upgrade on the 22nd October 2015 which will only expire 2017. i told her i never took an upgrade and nobody called me regarding an upgrade. she then referred me to Mtn store to cancel the upgrade but they couldn't help me when i got there telling me i must call Mtn call center to cancel. <br> I have been calling them today since the morning asking them to cancel this as it was done without my permission and my concern. the consultant have been telling me different stories all day not helping me at all. <br> <br>