What happens if an insurance company is delayed claims?

Hi, My husband taken sbi life insurance policy. I am nominee/wife. He was died 2years ago. We don't have children's. To claim policy money,i have submitted all required documents to sbi life after husband's death. My in laws send letter to sbi life to stop claim amount. After sbi life reacted and asking me, legal heir certificate to claim policy amount. I send notices from my lawyer. As a wife/nominee I have right to claim amount. I heard that if I send declaration suit to sbi life problem can solve. Please suggest me to claim policy Thank you