Nagtatagong seller

When i was in highschool, my mom talked with someone who claimed that she is "legal owner" of a land being sold. They negotiated the terms of payment went to a notary public, i think sworn statement kung papano ang magiging payment. The total amount was 270k. That was in 2001. That time, My mom was in nueva ecija and the seller resided in mindanao. May mom sends the monthly amortization to her as agreed. Most of time, she came to our house and signed the aggregate amount my mom has paid. But after, they lost contact. Last year, we learned that there was a claim won by a third party who is the truthful and rightful owner of that land. We tried to talked to the relatives of the person and we eventually got her contact number. We called several times but we are being dismissed. My family wants amicable settlement as much as possible but seems like it's not going to happened. The family of the seller has numerous alibis and obviously theyre hiding her. What we want is for our money to be returned. But we dont have the resources to pay a lawyer. What legal course of action can we take? Is PAO for free? Appreciate your detailed response.