Co operative society rules

Hi. Our agricultural land was mortgaged about 3 years ago in the co operative society bank, vandse, kundapura taluk, udupi district, karnataka state, india. This land is legally registered in the name of my mother. My uncle and my mother commonly share ancestral property as well in the nearby area. This mortgage was done deceptively by my uncle, who said that he would be taking an agricultural crop loan on the common ancestral property and got my mother's signature on the NOC. He has then mortgaged both the ancestral land as well as my mother's property in the co operative society and has gotten a loan of 5 lakhs. He hasn't paid the loan instalments more than 2 times, so now 3 consecutive notices have been sent to our ancestral home for the payment of the due amount. We discovered all this just 2 days ago, since we live in bangalore. Last date for payment of the due amount was 16th of this month. Could anyone please let me know what could be done to free our original property document from the bank? Also what are the next steps that co operative society banks generally take beyond this point?