I am also seeking Deleon's from the Philippines so I read your message. My husband just went through a similar search and found his father who is in the Philippines. The way we were able to do it was by searching the phone listings on a site called "pinoysearch.com"
We found my father-in-law the first weekend in July and went to meet him a couple of weeks later. We had a wonderful trip and my husband met his 4 brothers (whom he knew nothing about). It was wonderful. Good luck on your search. I have a person in Hawaii who helped us with our search who has a lot of expierence searching the Philippines. If that site doesn't have a phone number for you then let me know and I will give you his e-mail address. I've never met him, but he was a wonderful help to me.
One more tip... when we were searching we were spelling his dad's name wrong. As soon as we spelled it correctly, we got immediate results. We wasted so much time searching the wrong spelling! Make sure you know for sure the correct spelling of his name. Check your birth certificate if you have it or try several different spellings when you search the phone directory.