Vodacom fails to cancell my contract 6months later

I have a cellphone contract with Vodacom which ended on the 28th Oct 2014. I called the call centre to request that my contact be cancelled and converted into Prepaid - which was not done months later. I did not notice this in time because I'm paying for two contracts however i'm billed once for both. <br> <br> I'm still paying R139.00 p/m which i want to be refund off. Since you record our calls, go aback into your records and find out when I did submit my request. Then refund me from then ... else I'm cancelling both contracts and i sure will influence my parents and family to move away too, then my friends... Pooor pooor pooor service vodacom. Its unacceptable.