@mel.01.08
I advise you to show the Deed of Sale you have to a lawyer. The terms and conditions of that document will be material to what proper action you should pursue.
It is my understanding that you have fully comply with the terms and condition of the contract to sell. Hence, when the deed of sale has been executed, the contract to sell is automatically canceled. the contract to sell is superseded by the contract of sale; and, what will govern is the terms and condition of that contract of sale.
In short, the stipulation in the contract to sell will not be binding anymore. However, it is not the same as saying you will not be bound to pay additional amount if you erroneously received a bigger parcel of land that you are legally entitled to, pursuant to the contract of sale. This is to avoid unjust enrichment on your part.
As an overview, if the terms of the contract of sale shows that you are entitled to receive only a particular size of lot and if you erroneously receive greater that what is stated, you are bound to pay for the excess. This obligation is not based on contract, but an obligation created by law.
On one hand, since ownership of the land has been transferred to you (though not binding to third persons for lack of registration), the seller cannot legally compel you to take another lot in exchange for what you currently own. However, if you agree, there is no law prohibiting the same. In fact, compromise is encourage.
Hope this will help.
Happy New Year to all!!!