Discovery medical keeps on deducting after cancellation

I cancelled my medical aid with Doscovery in November 2024. They still deducted the instalment on 1 December. Received email confirmation from them in December that the medical aid has been cancelled. They then proceeded to deduct the instalment again on 2 January 2025. Totally unacceptable as I have to go into the bank AGAIN to reverse the debit order. Perhaps Discovery can explain why they keep on deducting monies from my account after cancelling my contract with them?