Lost for words

Medical aid cover was cancelled 31.03.2020 and 90 days letter I Receive a letter from Bonitas REMINDER-OUTSTANDING DEBT [MI***]” I would like some more clarity regarding the amount owing above an I also require affirmation in writing of any clauses in the contract I had with Bonitas regarding you having to pay the scheme back for claims that has already been paid prior to a cancellation . I just want to get some clarity because according to my understanding I gave notice on the medical fund to join a new medical scheme due to the terrible service from Bonitas and let me not talk about the Co-payments .

I also just want to know if it is standard practise for you to bill people after cancellation because my mother is with you guys and god forbid if she must be hospitalized and you pay for her hospital stay and she should pass away and the cover should cancel would you then send a letter like the one attached for us to settle “ REMINDER-OUTSTANDING DEBT [MI***]” , Because you are now asking me to settle an amount for God knows what after you already accepted me as a client paid for the claims while I had active cover and now that the cover has been cancelled you send me a letter 90 days letter to pay you back. I have paid every month premiums without fail so please explain to me for what I owe you money . I take cognisance that we are working through a pandemic that is prevalent over our country however I would appreciate it if you could put some effort into my query