Bought a land with acknowledgment receipt only

We purchased a portion of a parcel of land and since it is still being paid to pagibig, we agreed that we will just issue an acknowledgement receipt and do the deed of sale later. However, the owner decided to decrease the portion that we paid for. if we will bring this to court, what proofs or evidences can present. We have text messages exchange showing his change of mind can we use that to court? A lawyer advised us to sue for specific performance. Hoping to hear some clarifications and advice from the community.. Thank you

Mahirap ho talaga magtiwala sa panahon ngayon. I learned the lesson the hard, painful and expensive way. Yung lupa involved here is parte ng 500 sqm na narimata ng bank. Kasama kaming kausap ni Mr. AH (guess what it means ) sa pagtubos sa bank.Ngunit dahil 50 sq m. lang ang interes namin dito ay nagprisinta si Mr. AH na ipapasok nya sa Pagibig ang pagbili at sa kanya na lang daw namin bayaran yung parte namin. After 1 month nagfully paid na kami kasama na yung gastos nya sa pagtransfer title from bank to Mr. AH. Mas mataas ang siningil nya sa amin per sqm kumpara sa pagkabili nya sa bank. Naintindihan namin yun kaya we did not complain.

Nagpirmahan lang kami ng isang acknowledgment receipt ( i know... who does that). At ito pa, hindi ko naspecify dun sa receipt yung exact location ng lupa. (again...stupid, right?) Kasi nga i was thinking na pag nasukat yung lupa for subdividing saka ko malalaman yung tech description ng lupa. Saka ako gagawa ng Deed of Sale dun sa fully paid namin part of the land. Kasi nga feeling ko sa kabaitan ko sino ba magtatangkang lokohin ako.

Eto na, nagsusukatan na kami ng lupa with the Geodetic Engineer, biglang nagdedemand si Mr. AH
na kumurot ng ilang sqm dun sa kinuha namin. E hindi talaga pwede. Hindi naman sa nagmamaramot pero basta may dahilan. Aba, at nagthreat si AH na since nasa pangalan nya ang titulo at since hindi nakaspecify sa receipt ang location ng land, sabi nya sya daw ang masusunod. To h#&$ with our agreement, and to h#&$ with our karapatan. I asked him to sign a Deed of Sale na with the tech desc dun sa original na usapan. Syempre being an AH, ayaw nya pumirma.

So what to do? I was advised to file for civil suit with specific performance. Pero sinabihan din kami na pwede pahinain ang case namin kasi nga receipt lang. So it's up to God's graces to be bestowed on the Judge to be enlightened sa aming appeal.

Pero humabol pa si AH...di mapigilan. Tinawagan ako at sabi na magdemanda daw ako. And he said na may lawyer daw sya at 100,000 daw ang babayaran namin para sa lawyer nya. At binigay na rin nya mga plans of action nya sa lupa na binili namin (sya na daw kasi ang mananalo). Either isosoli daw nya yung binayad namin or igigiit nya yung hinihingi nya portion sa lupa na binayaran namin.

I have some text messages that can prove that he was trying to renege on our agreement. Is that admissible in court? Sa NTC ba hihingin yung proof of ownership ng number kung sakaling postpaid sya. Mahirap talaga pag feeling Dyos ang kalaban mo.