Land boundary issue

Hi, My father bought a house before 22 years back during that I am not sure how did he managed to measure the house boundaries. But I see a conflict where our pipelines being planted on top of that the house beside us have their sunsets of windows. Now after these many years suddenly the person who reside was about to sell his house and came up with an issue saying that small part of the land belongs to us and your pipeline needs to be removed. Can you please help us how can we resolve this issue. Thanks