illegal occupancy

Sir My father has a house in central delhi which was registered in his & his mothers name in 1974. & being a joint family my father alongwith his 6 brothers( including their families) were staying in this said house. during 1990-2000 this perod 5 brothers bought their own house & shifted including us but 1 brother & his family stayed there in that house because they could not afford to buy their own house on their own. & so as they stayed in that house & whatever electricity bill,water bills & house tax bills( which were in my fathers name) they paid. ( pls note: we were not charging any rent from them ) in year 2004 my fathers mother expired but we didnt change the title of the house after her death. but now we came to know that now the electricity,water bills are coming in their name ( they transferred names in electricity,water dept.) moreover they have shifted to new house in faridabad whhich they bought on their own & have rented the same house without my fathers permission( which is my fathers name ) to 2-3 tenents & charging rent from them. now sometime back when my father asked them to vacate the house they refused & said we have no right on this house as they are paying electricity,water, house tax. but now we want to get that house vacated & sell the house.what can we do . please suggest.-- thank you