Property sold by making forged documents

An alleged builder and an engineer had made a 4 shop complex by getting sanctioned to the Map of that building by Municipal Corporation of the city. But actually they made 6 shops instead of 4 as described in Map while getting approval of Municipal corporation. Now they sold shop no.2 to my father in the year 2005 in cash 2 lacs rupees , by a registered special power of attorney , by making forged Map of that building they also submitted that forged map to the registrar office for registration...Actually on original Map shop no.2 is different & on forged Map which they sold us shop no 2 is different. In spite of all these , We tried to sell the shop but due to their bullying nature no one is ready to buy the shop above 2 lacs rupees till now. Now , When I collected original map from the Corporation , we came to know about the fraud played by them to us. They have caused so much mental , physical and irreparable financial loss to us ..Now we want to teach them a lesson by doing all possible legal proceedings and need help from all of you guys to set an example for such Leach of Community who are engulfing huge amount from innocent people and causing them irreparable loss... Regards