Unpaid loan from a lending company

Good evening. I'm jeffrey. i would like to ask and request for a legal advice regarding my financial situation and problem. Nakautang po ako ng 100k sa isang lending company. I signed in the contact and agreed with its 5% monthly interest. We also had an agreement that I would pay only the interest of the principal loan amount monthly since I was incapable to pay yet both the capital and monthly, and this situation would continue until I have already paid completely the principal amount. For 1 month, I was able to pay the interest of Php5000 but for the succeeding 11months I have failed to pay because of some emergency situations that required me to spend my money. After a year, I was called by the lending company through a summon. In their office, I explained why I have failed to pay my monthly dues. Then, the lending company manager decided to just add up my unpaid interest within 12 months which was P60,000 to my principal loan amount. So as of now, I already have a principal loan amount of P160,000 and they continuously require me to pay the interest monthly. Is this legal? Can they do such action and move without violating any legal debt rules/laws and borrower's rights. I really need your advice and help. Thank you very much.

may case is bp 22 sa lending company un brother ko umaatend dahil nasa abroad ako now my brother is in abroad too at nakatanggap ang sister ko ng arraignment letter this coming august pero walang alam ang sister ko about the case paano po ang dapat namin gawin pareho kaming nasa abroad pwede ba kami pagawa letter sa abogado since pareho kaming wala ng brother ko sa pinas. thanks po