Sell resident home at Kharar

Sir, We have a Double story Home with Valid half- half property registration between both the brothers. Thereafter, we have a mutual agreement that the ground floor owner I the younger brother because he lives in this portion with their family and first floor is the elder brother. He resident in Delhi with his own flat for past 15 years. We want to purchase the first floor since 2002 but he always refused to sell us and told that sell it outside. If we find any buyer then he increases the rate each time. Now we are totally frustrated what to do. Can we sell our Part (Ground Floor) if someone is trusted to buy without any legal complications, or how to buy 1st Floor because each time he increase the rate. i.e Total value of House 18,00000. 50% share for each 9,00000. We offer him that you purchase the ground floor, he also refuses to buy with this rate. Currently sell Floor system not start at our location but as per requirement some buyer want to buy. Please help Regards Mohan