Not canceling my insurance as requested

phoned to cancel my insurance policy in my old device was told to email *** as i cant do it over the phone so on 18th October i sent a cancelation of insurance request, no response so on the 7th November i send it again received a email only on the 17th of November that the policy will be canceled and "telkom requires 30 days notice of cancelation" now January 4th received a invoice for device insurance... ***