apollomunich health insurance co ltd - REJECTION OF HEALTH INSURANCE CLAIM

i am from Gangtok - Sikkim. in **** one of staff from Bandhan Bank Gangtok Branch suggested me to buy apollomunich health insurance combo pack for my family. as he is known to me for years i bought it. he did all paper works and as
formality took my signatures on the policy forms. in ****, my wife had to undergo heart valve replacement surgery at Neotia Hospital Siliguri. after her treatment, i submitted all papers and bills to the company rep who visited us personally.
the company rejected my claim on the ground that pre-existing condition was not revealed in the policy form. the company also sent me letter of termination of my policy with immediate effect. a few days later a sum of Rs ****/- was credited in my account from the company. since then i have been writing them but so far there is no response.
my policy No. PEO*******
Claim Id *******