Angry customer

I had a device insurance on a handset I bought from MTN early 2020. I cancelled the policy in July since my handset was insured with my home contents. To this day I am sill being billed the insurance premium. I phoned the MTN insurance department and was told that the insurance was cancelled but they couldn't stop the debit because it has to be done by MTN customer service. I sent proof of billings for 6 months to the MTN claims department. Im still waiting for a resolution of my query, 4months down the line. Worst service ever.