Vodacom Insurance Not Cancelled after several attempts

This is regarding the "attempt" to cancel Vodacom Insurance on a cellphone. End of June i contacted my service provider where i have contract for my cellphone. i managed to downgrade my contract and wanted to cancel the insurance on the phone - obviously to save money! I was given a number to call for cancellations of Vodacom Insurance. i called and they confirmed the insurance would be cancelled. July came and i was debited again - called again and they confirmed again that insurance would cancel. August debit again - i phoned again and i was told, Sir you had to send us an email to confirm cancellation. What! i was never told of this before hand. Anyways i duly sent an email believing finally we getting to the end of this. September came along and yip i was debited again for insurance. I called again and was told that my insurance was cancelled but they do not know why i was debited. i was told to send an email to ask for refund. Needless to say the emails keep returning. im at the ends and have no idea what to do. i would like my refund and confirmation on cancellation in writing.