Inherited lot sold but not fully paid

What can be legally done in this case?

A parcel of land owned by my mother had been sold to my niece. My mother signed a power of attorney for me to take care of the transaction ( selling). Me and my niece agreed a specific price however she didn't pay it all. I signed a deed of absolute sale, however not notarized yet that time stating the full amount of the parcel of land trusting that my niece will keep her word of paying us the balance a month after the transaction was made. I tried to contact her through text and call to get the balance but she wasn't returning my call nor texting me back. She is nowhere found which I think she is just trying to turn her back from the amount she still owed us.


Knowing that the property is an inherited lot by my mother and I was the only one who signed the deed of sale. Do you think that is already legal and binding? What move can be best done on this case to stop them from building a concrete house in that said land.

thanks for the help!

is this property titled with at tct?