Niva bupa health insurance - My son Aurian hospitalization bill claim

My son Aurian, ** years old was admitted to Kanchi Kamakoti Childs Trust Hospital (KKCTH), Nungambakkam, Chennai for having breathing problem during night times for around ** days. He was admitted since his oxygen saturation level was marginally lower around **% (normal range being **% and above). He was given nebulization plus oral steroid to improve his breathing and to reduce his IgE level. He was confirmed with mild fungal infection (ABPA) in his lung. So he was prescribed with anti-fungal infection medication for six months, plus periodic post hopitalization Liver Function Test and IgE level test to ensure that the steriod is not having any harmful effect on his liver. He was admitted in the hospital for five days amounting to a bill of Rs. **,***/-. Niva Bupa insurance company rejected our claim citing he had past history of febrile seizure. I tried to explain to them that the febrile seizure he had was when he was around one year old on account of high fever (~***F) and for the last nine years he never had any seizure. Moreover, this time he never even had any fever, what he suffered now is the respiratory problem. They are trying to connect the dots with the high fever to the respiratory problem he had now. The pulmonologist Dr. Vijaya Kumar whom we consulted at KKCTH had clearly stated in his letter to the insurance company that this respiratory problem is a separate entity and in no way related to his past medical records.
I raised a complaint at the consumer grievance website and for that Niva Bupa replied to provide us the documents related to the fibrile seizure of his earlier episode. We were in Singapore at that time and don't remember we having any documents related to that, even if we had kept any, have lost when we moved back to India five years before. They said they will reply to my mail for their request by **th of this month. Shall I wait until **th of Feb'** for their reply or shall I go about filing the complaint with you?
Thanks.