Jejecting Start / Joining date.

I have recently joind Discvery Medical Aid, i fact a few days ago, from another Medical Aid, i ended membership of the previous Medical aid, which in fact ends on 31/10/2023. I have requested Discovery Underwriters to please ammend the joining active date to 01/11/2023. Yesterday i received communication that the request was rejected because according to Discovery i am still an active member on my current medical aid until 30/11/2023 which is not true. I submitted my membership certificate from the medical aid clearly stating my membership and benefits end on 31/10/2023. Why is Discovery refusing to ammend my start / Joining date to 0111/2023 ?