Eviction of rented flat

Sir My father along with his brothers had bought a piece of land whereupon they together built a building. Each of them have a flat each having a individual holding number. Since it is between the family, my father would simply take the rent from his elder brother without officially taking it from the tenants. Now my problem is- 1. Since 2011 my father's elder brother is not handing him the rent. 2. We had spoken to the tenants(A real estate Company) but they are not willing to pay us the rent, moreover they are also not willing to sign a fresh agreement with us nor are they willing to vacate the property. 3.We also asked the tenants to provide the agreement papers on the basis of which they are occupying the flat. But they are not giving us the papers.. Documents available with us in my father's name :- 1. The registered deed of buying the property. 2. The municipality tax receipt of the holding number. 3.the electricity bill ***Note- The tenants have never signed any agreement with us since inception. - my father had not given any right(issued NOC OR POWER OF ATTORNEY) to his brother) What are the various avenues (both Criminal and Civil) on the basis of which we could force the tenants to come to agreement with us..