Religare rejected my medical claim

Religare not giving my 6.4 lakhs claim on the grounds that it was pre existing and that I didn't disclose my hypertension n diabetes. I had lung infection and was operated at Max Saket delhi I purchased the policy in December 2015 thru indusind bank. They came to my home to sell this policy and asked me to just sign the form and rest they would fill. I hv hypertension for last 10-15 years. But re diabetes i was once diagnosed with borderline sugar in 2012. The doctor advised that i just manage my diet but when i told him that I travel a lot then for precaution he advised medicine for some time. I took that medicine for a few weeks and then stopped. I didn't take any sugar related medicine for last 3 years. I acknowledge that hypertension should hv been disclosed but not diabetes as i was not taking any medicine. I have already provided Doctor certificate that it was not pre existing and that my lung disease was not caused by diabetes Religare also sent their doctor to my home to verify facts. He saw all docs and interrogated me n took my n house pics Yet they continue to reject my claim. My point is that first the non disclosure is a genuine oversight as i was just asked to sign the form. Second even know if I was having both hypertension n diabetes, even then i shd be paid as none of these diseases causes lung infection Please help and guide me whether my case is strong n how do i get my claim passed. Regards. Rajiv