In general, a buyer in a perfected contract of sale needs to register the deed of sale covering the transaction in order to bind the land against third persons. This is in accordance with Section 51 of Presidential Decree 1529, as amended, known as the "Property Registration Decree," which states that:
"An owner of registered land may convey, mortgage, lease, charge or otherwise deal with the same in accordance with existing laws. He may use such forms of deeds, mortgages, leases or other voluntary instruments as are sufficient in law. But no deed, mortgage, lease, or other voluntary instrument, except a will purporting to convey or affect registered land shall take effect as a conveyance or bind the land, but shall operate only as a contract between the parties and as evidence of authority to the Register of Deeds to make registration.
"The act of registration shall be the operative act to convey or affect the land insofar as third persons are concerned, and in all cases under this Decree, the registration shall be made in the office of the Register of Deeds for the province or city where the land lies."
The above-mentioned provision of law may be availed of by the buyer if the owner's duplicate of title was surrendered by the seller. In case of refusal of the seller to surrender his or her certificate of title, the appropriate legal remedy is to file an adverse claim, as mentioned in the case of Logarta v. Mangahis (GR 213568, July 5, 2016), where the Supreme Court speaking through Associate Justice Estela Perlas-Bernabe, stated that:
"Thus, the prevailing rule is that voluntary instruments such as contracts of sale, contracts to sell, and conditional sales are registered by presenting the owner's duplicate copy of the title for annotation, pursuant to Sections 51 to 53 of PD 1529. The reason for requiring the production of the owner's duplicate certificate in the registration of a voluntary instrument is that, being a willful act of the registered owner, it is to be presumed that he is interested in registering the instrument and would willingly surrender, present or produce his duplicate certificate of title to the Register of Deeds in order to accomplish such registration. The exception to this rule is when the registered owner refuses or fails to surrender his duplicate copy of the title, in which case the claimant may file with the Register of Deeds a statement setting forth his adverse claim."
So if the seller refuses to hand over the title, applying for the annotation of your adverse claim is proper under the circumstances.
Source: Manila Times