Fraud against property breach of trust

In 2011 my mother purchased a property through my cousin brother from his friend and my mom gave 13lakhs cash where in 10 lakhs were given to the owner and 3lakhs to my cousin, property was finalised in 20 lakhs, so 3lakhs were taken by cousin as he stated he will be keeping that amount on interest and he will be e paying off the remaining 700000 by the interest amount property on first January 2012 after 2 years we got to know that the property is been mortgaged by the owner he haven't paid the emi's, when asked my cousin and the owner replied that they would be closing of the loan and would be transferring the property on my my mother's name. And I asked for the remaining amount this is how we kept paying him the money e and on June 2015 we almost paid the the entire amount and they bought a stamp paper of 500 rupees and made a written agreement mentioning the above amounts and promised to to transfer the property within 6 months. It's almost been nine years now we are just following