Room rent limit causing claim deduction - need advice

My father was hospitalized for 12 days for cancer treatment. The total bill was 8 lakhs. My health insurance policy has a room rent limit of 2000 per day, but the hospital charged 12000 per day for the room. Because of this room rent capping, the insurance company has proportionately reduced my entire claim and only paid 3 lakhs. I had to pay 10 lakhs from my pocket. I did not know about this room rent proportionate deduction clause when I bought the policy. Is this fair? Can I challenge this? Should I upgrade my policy to remove room rent limits? Please advise.