Family land selling dispute

Hii I am from rajasthan and behind our house there is a plot of our family member (grand father's brother) And we are using this land from 26 years as they dont stay here and gave permission to use the land many times we asked them to sell but they refused and one day they sent a legal notice saying "we want to sell our land and u have the first priority to purchese as you are taking care and using the land so if ur intrested in buying the land in market price then u can do it otherwise ill be free to sell this to others" We also replied via legal notice that many times we asked you to sell the land and you refused and we sent the quatation of current market price to them And then there was no reply from them now he is saying that he will not sell the land in any price to us and he will sell it to other and asking to free their land What should i do now We really need this land and taking care of it from 26 years