Gems refuses to pay

I added both my parents on my medical aid.. After my mom retired and had to cancel the medical aid they were on.. I waited for the 3 months waiting period and paid my account in full. My father had started being sick before and we used to take him to our local Gp.. There was never a disgnosis on his sickness.. Our GP promised to refer him as soon as the medical aid was active. Coue of days after he got active.. Unfortunately he got really sick.. It was in the early hours of the morning and we couldn't send him to the gp cs the surgery was closed.. We then called an ambulance and sent him to a private hospital which is 2 hours. away from home. There is a doctor that assessed him in my presence and asked how long has his arm been shaking.. My dad gave aa rough estimation.. They did a full assessment and the receiving doctor told me that my father has parkeson's disease which is chronic.. That was the very first time I heard what was actually causing the shaking n joing problems.. He got admitted.. A physician requested scans to be done but gems refused to pay.. Gems refused to pay for his hospital stay.. I had to go collect him on his sick bed. When I called gems they told me the underwriters are still investigating if I Ddnt disclose his condition.. I told them that I had no idea what disease he had since he never took any treatment and our GP never diagnosed him with such.. Now gems is refusing to pay everything concerning the treatment of my sick father.. I was told to go and get a motivational letter from my local GP.. But my problem is my dad is currently very sick and I'm not sure if Gems is willing to assist me!! Please help