Legal heir

Sir, I am trying to get my fathers legal heir certificate for the past 5 years. My father is a tamilian who is from the tuticorin dist, Tamil Nadu However he lived all his life in Vazhappally, Changanacherry , kerala Before he died he had an accident and had to stay in Munnar which is in idukki dist. where he passed away. The death certificate was obtained from the munnar hospital with the address of munnar where he lived at that time. Later i applied for a legal heir certificate in Vazhappally, Changanacherry i was denied the certificate stating that my father died in munnar and has the address of munnar in his death certificate there fore have to go to munnar to obtain the death certificate. When i approached the tahsil he denied that saying that my father lived all his life in munnar so he need to get a legal heir certificate from them. I got it in writing and went back to the Vazhappally, Changanacherry taluk office. they again denied it saying my fathers roots are from tamil nadu and therefore i need to approach them to get it. I travelled to tuticorin and met the tahsil who denied the fact saying that there is no proof that my father ever lived in tamil nadu. He was right from his point. However he was not willing to give it in writing. I explained the same to the Vazhappally, Changanacherry tahsil and he denied again saying that i need to get it in writing. I travelled again and again for the same for years and finally managed to get it in writing. When i approached the Vazhappally, Changanacherry tahsil He took the document checked it and says that the file is lost some where. He asked me to give a fresh request. So i did it and now he says that he need a writing from the munnar tahsil. What should I do now Is there any way i can get the legal heir certificate