My Uncle's are not giving the documents of my father's property.

How should i claim my share in my grandfather's property-Divided in his three sons: My 2uncles and my father, my father was the youngest one-He passed away in 2003. We live in a joint family & my uncle's are not giving any document related to the properties. Even they sold one plot of 200sq metres which was of my father's share promising that they will give us half share of the payment, My mother agreed and signed in a way that atleast we are getting something rather than nothing, but later on they gave us only the 1/3 share saying that we helped you in every circumstances after your father's death and need money. Now i need help that what should we do - we are three siblings-me(youngest brother) my elder brother & sister(married), we have 3 properties left which is in share of three son's of my grandfather and my uncle's are not giving any documents to us and also not showing any interest of giving our share to us in future. We tried our best in even compromising with them & with talks there is no effect on them. If there is any court case we can go for? Or what measures should we take to get the share of the property? I hope now you can assume our condition and may do a help. Thanks.