Fraudulently change name in patta

My ancestors agricultural property in tamil nadu India has been fraudulently change name by my cousin few year ago. Actually there are two parties claiming this property now.Me and my cousin are the one claiming for this property now. My self and my cousin came to an agreement and he agreed to return the illegally changed patta back to me. But recently we caught in fight and not in good relation anymore. I'm actually a Malaysian citizen. Its actually my ancestors property from my father side.For more then 50year no one claim and change the patta name from our side. Suddenly came to know that my cousin changed some patta to his name by fraudulently claiming that its his grandfather property. Since his grandfather name and my great grandfather name is same he easily claim that property fraudulently without my knowledge. In this situation what I should do? After I came to know about this matter I appoint an agent to help me to settle all legal matters regarding this but till now haven't settle yet.I just waste my money to him till now. Hope can get clear idea from your team. Thank you.