Land dispute problem

Dear sir/Madam My father purchase a land from the owner and original paper and mutation work on my father name is done but the problem is that land was captured for 40 years by land owner relative whenever my father tries to make home all the time that person file some 144 law due to that construstion work getting distrubed when my father ask to the owner the he told that once your will to lintel level he will be unable to file 144 . I want to know that he is speaking right that after lintel level no law is there to stay on our construction work and also when we enquire the main case is going on in high court and also he is ready to return our money as we already invest around 3 lakh rupees we are unable to take some decision . please suggest what will be better take our money back or wait and approx how long it will take for this case. intially when we purchasing that land the there is no problem with the land as he cheated my father so is that any law to for compensation for this cheating. Thank you