Broker Cheated

In 1996 we purchased a piece of land measuring 8 Marals as per rate fixed @Rs 5000/Marla through a broker. He gave full possession. He demanded full payment which we made. For about a month he didn't processed papers for registration. On our persuations and pressure through our society he gave registration for 5 Marals only and made a road through the remaining and demarcated land of 3 Marlas. We had been asking him either gives us the land or give the money back from time to time. The broker was a cheater dishonest and noitrous rogue who took advantage of our simple nature he had been avoided us on one pretext or the other till he died in 2015. After 25 years his son comes to us that we have occupied more land he is a gunnda/Lofer like his father he comes off and on and threatens us. Fortunately, the road passes through the land which is shown in registrated documents now we decided to sue the man but we were told it will not be accipted in the court after 25 years now kindely guide us how