Discovery Health KeyCare Income verification

Last week my husband received a sms from Discovery Health, informing him that our monthly premium will increase from R2978,00 to R6708,00 on 1st February. We have been with Discovery for over 10 years and expect a slight increase in our premiums at the start of a new year, but this increase has more than doubled. After attempting to call Discovery for more than 2 days, I finally reached them. The consultant informed me of their new income verification form and emailed it to me. My husband and I promptly completed this form and emailed the necessary documents to them. I received reference numbers for this, but no further communication. On Friday 26/1/24 I called to query the outcome status of the procedure and was connected to a consultant in their income verification department. I gave her all my reference numbers and she perused our documents. She told me that based on my husband's income, our new premium, effective 1/2/24, is R4542,00. This is shockingly R1564,00 more than our regular premium. I told the lady that as semi-retirees, we cannot afford this huge increase. She said that the premiums are income-based and this, unfortunately, is the premium for the income bracket for my husband. His income is R210,00 over the cut-off for the lower income bracket, which would've allowed and increase of R619,00. I told the consultant that premiums cannot be calculated only on income, that other living expenses needs to be considered too, such as monthly payments for electricity, municipal account, groceries etc. She informed me that Discovery Auditors calculate their members premiums based solely on income. I informed her that unfortunately we cannot afford this huge premium and need to cancel the medical aid. She said a cancellation must be done one month in advance and that the new increased premium will be deducted on 1st of February and March, should my husband email our cancellation request now. How can a huge company like Discovery calculate affordablity without an Income AND EXPENDITURE form? Surely premiums cannot be based purely on income alone? We are now trapped with two exorbitant premiums for the next two months, as Discovery refuses to acknowledge their fault with their income verification procedure. This entire process has been sprung on members without, at least, a few months warning. Is this legal?