Land dispute with relative : gifted property

I am from Kottayam in Kerala and have a dispute going on with my close relatives who are also our neighbors. My father had a plot of land measuring 80 cents (0.4 acre). He divided this land in two and gifted to my brother and me. As per my official property ownership document, I’m supposed to have 60 cents of land. I would like to quote the exact words written on my brother’s document. He “has ownership to 1/4th of the land which is 20 cents”. About a couple years ago, while trying to build my house in the said 60 cents, I had private people survey the land and understood that the total on both our lands is actually not 80 cents. They measured it to about 76cents meaning we are short of 4 cents total. I live out of the state and while I was away, he has taken the whole 20 cents that he owns and build a boundary wall. Is he right in doing that? Why should only I lose out for what is not on the official document? This could be a measurement error that was done about 40 years ago. If I were to go to court with this what are the chances of winning? Is going to court the right way to go or should I approach the police department? Please advise as this is my first encounter with the legal realm of life.