Land problem

Hello sir/Madam Actually my father purchased a some a year before from land owner and they got all the original papers and mutation work also completed but from is that the land wchich my father purchased from the owner actually captured my some body for 40 years and now whenever my father wants to start the work that party file a case something 144 law and when my asked to the land owner to clear they said that once your work will be done upto lintel level then he cant do anything. I want to know one thing that is this right that once my work will reach to the lintel level no laws can to the construction work, work will goes smoothly or their is some law after reached to lintel level also and one more party who captured the land he is also some paper.land owner is ready to return our money but we want actual rate ..please suggest us wchich one will be better.