Charged for service after canellation

About 3-4 months ago I got rid of my Blackberry 9810 and replaced it with a Blackberry Z3. Because the R59.00 per month BIS subscription is not available on the Z3, I cancelled it before putting my SIM card into the Z3.<br> <br> All was well until yesterday when, out of the blue, I received 17 messages telling me that R59.00 has been deducted from my airtime for my monthly BIS subscription, and indeed it seems that the amount was taken off my airtime.<br> <br> I find this utterly unacceptable and expect Vodacom to refund my as soon as possible.