• Fradulent aquiring of land property by relatives

I had purchased a ready built house in East Champaran in Bihar in the year 2007.      Subsequently after purchase of the above House, my own elder sister requested me to allow them to stay in my above house for schooling of their children and also promised to look after my house. Since we were staying out side of our home town, we agreed to their proposal and they started living in my house from May 2007.  A part of the above house was also given on rent to some other students and the rent amount was being collected by them.  After few months of stay when I enquired about the rent amount, my sister and brother-in-law told that all those amount have been expended on repair to the house, fitment of a hand pump and clearance of drainage.  As myself and my husband both were living away from the above place, I had to believe on them and remain silent over the issue.  Again after few more months when I enquired for the same they come up with some more excuses and tried to escape from paying the amount.  Despite all above on their saying I had deposited some amount recurrently into their Account for purchase of Asbestos and to undertake certain required work in the house.	Since they are my own elder sister, both myself and my husband were having a good sense of faith for them.  Even I used to keep my jewelry and other costly items with them to avoid robbery while travelling and while living outside.  By taking advantage of our faith on them and that of our prolonged absence from the place, on Feb 2012 they reported me on telephone that somebody from the nearby is claiming to be the actual owner of the house purchased by me and they would occupy the house forcibly, since they are having the documentary proof with them. Such a sudden prospect of losing the property scared us and under the guidance of my sister and brother-in-law, We agreed to sale of the plot to a third party, who could be able to withstand the claim of the prior and thus we could be saved from losing our money on account of house.   The sale of the house was perpetrated by my sister and his husband so hastily that, We had to accept the deal at an initial payment of Rs. 2,00,000.00 (Rupees two lakhs only) while registering the house to the third party against the deal value of Rs. 13,50,000.00. The payment of remaining amount was though guaranteed to be cleared with in 01 month, only Rs. 5, 74,000.00 was paid to me by my sister after three months and the same was credited to me through bank. The balance amount has not yet been paid to me and after few months of time I came to know that the house has been re-registred in the name of my sister which clearly speaks of their malicious intension to grab my property.  
Request suggest me, how to take remaining amount of money from the purchaser or my sister. I have documents proof for all the above details.