Delay in Gratuity

Dear Sir / Madam, I am Sudha Sharma, currently residing at Kolkata, My husband worked in NPCC India Ltd. as a Civil Engineer from 1975 to 2000, after the death of my husband in the year 2000, I have applied for the gratuity, pension and CPF. The company asked me to submit the legal heir certificate from competent authority, in 16th Nov.2000 because they have found other name in personal file record of my husband which was confusing for them to find out who is the legal heir but they asked me to submit the legal heir certificate after that I have submitted the Succession Certificate from 1st Class Magistrate, as per their request , then I have waited more than 17 years but there were no reply from company , and I am Illiterate and it was very difficult for me to look after these matter with my 4 little children, in the year 2017 I have found all the related documents then I applied again for all the due amounts and they have released my CPF amount of Rs. 5,73000, but now I am waiting from last 1 year for my Gratuity amount and Pension , I have submitted all the documents trough email and hard copies through courier to the head office located in Faridabad , and I have been calling 3 to 4 times in every week to the head office and other branch office from last 1 year , and they are telling me that we are not able to find the personal file records of Lt. Dhaneswar Sharma and in absence of personal file we are not able to take any decisions. I have also sent all the supporting documents through courier, but they are not taking any decision and I want going through a very poor situation. please suggest what to do now ?