FNB Hospital Plan very very bad service

My brother Khayalihle Mapasa was injured on the 6th April 2019. He was at Union Hospital until 31st July where he was released to rehab in Rosebank and later died. We made a claim for his children at FNB Hosptal plan. They asked for all sort of documemts. His hosptal bill was over R2.6m and FNB consultant said they will pay R18 000. To date nothing has been done. FNB keeps calling asking for letter of authority which I sent and still no payment. I am appalled at how FNB treat paying customers. I would advise anyone to rethink if they are going to take this policy. Shocking service. There worst part is that they acknowledged the claim and "closed" it whilst still waiting for letter of authority. Its been over 2 years now and no payment.