Health insurance for mother

Hi,

I have comprehensive policy for my mother with Star health since 2020 for sum assured as 5 Lakhs. My mother got PED like BP, Diabetes, Hypothyroid , heart attack and so. I declared everything and base policy got approved with waiting period of 3 years for PED.

Now only one thing got added recently is knee pain apart from that rest of PED is same. With this situation, i tried to apply top up policy for 20 lakhs with star health and they denied stating the PED so we cannot approve top up policy. I have few questions related to that.

1) Is it fair reason for them to deny top up policy though my mother is having base policy with them with exact PED till date except knee pain ? Or do i have any option to defend that ?

2) Given this situation, what option i have to get adequate coverage for my mother ? She is 64 years old. I am thinking 5 lakhs sum assured is low in current days, what options i have to get better coverage even out of star health or within star health ? I am paying around 30000 per year for 5 lakhs sum assured with comprehensive policy.

3) Am i thinking too much and 5 lakhs is more than enough ?

Please help me with your thoughts.