Hdfc Life Insurance - Repudiation of claim

My father had two loans with different banks , First loan was on commercial vehicle of INR *,**,***/- , and second was a LAP Loan from IDFC FIRST BANK of **,**,***/- . My Mother and father are illiterate and both of them have just learned to make their signatures. My father had loan insurance policy of HDFC LIFE INSURANCE company. Unfortunately my father died a natural death on **/**/****, he passed away in the morning **:** am in the sleep. Both the policies were same so both covered natural death , however when we claimed for insurance , we were only given money of First insurance that is Commercial Vehicle Loan Insurance , but the company denied to give the second LAP loan insurance on the medical basis stating he suffered diabetes while in the proposal form they have filled no in that column. My father never concealed any facts about his disease , which is why we were given first loan insurance , however in the LAP loan insurance company employees have charged us hefty amount of insurance amount and also hide the facts. My father and mother were illiterate so they could never read the documents which were in english , however my father never hide any fact about his diabetes to the employees. The clear prove that my father never hide any facts are clearly indicated as we were provided with the commercial vehicle loan insurance , however to sold their loan insurance to us which they stated was mandatory to take else pay the processing fees of ***** INR to the bank if we do not wanted insurance and the loan will be cancelled , so my father took the insurance which costed ******/- to save ***** rupees. They clearly misused my father and now they are mentally torturing my family . This is grave injustice being done to us .
loan account no. of commercial vehicle loan :- ********
policy no. :-PP******
loan account number of Lap loan :- ********
policy number :- PP******