Pathetic service

I'm exiting the fund through my employer group and moving to my personal capacity. I have confirmation from my employer that the withdrawal is effective 31/12/2023 BUT Discovery is insisting that the effective date is 30/11/2023. They have now initiated my personal cover from 1/12/2023 which is incorrect. Essentially I will be debited twice (from personal account) and employer as they are deducting this from my salary this month to pay Discovery 01/01/2024 for December membership. I've gone back and forth about this query and have not gotten any resolution to this. Discovery needs to correct their information.