National Insurance Company — mediclaim not granted

With due respect i would like to state that on 24.05.2019 my wife dolan mondal was suffering from severe headache and admitted to health world hospital, durgapur. I have a mediclaim policy under national insurance company. My policy no. Is [protected] and i was applied for a claim for the same. But on 25.05.2019 i was informed that my claim was rejected as per information that the patient could be treated at opd. As a result the hospital got a denial letter and forwarded to my email. But as my wife was in still pain and under the treatment of hospital, they informed me that her treatment is under process and they've to go through some more investigations. At last they took some fluid from lumber and got a result that there is some viral infection into the brain. As per doctor advice i came to know that lumber puncture could not be possible at opd. Hence i hospital was treated her in indoor basis.
After i got the first denial letter on 25.05.2019, hospital once again process for the claim because of the lumber puncture which could be possible without getting indoor treatment. But it was denied again and when i mailed them and asked for the reason for the deny they did not furnished any kind of information to me.
Now i just request to you that please take action in this regard that why national insurance company avoid to issue the 2nd denial letter and obliged.