Since there are security guards everywhere, why not just stop and ask them for a phone number to contact the company? If they are standing in front of McD's or other large businesses, then that's a pretty good indication they are reputable.
Sentinel Security Agency in Cebu are very reputable and they send their guards all over the country too. Very well trained by ex-military. I know two politicians in Negros who uses them and are happy with their services. They’re used mostly by banks or mining companies.
032412-4830
Do you need a guard for your business or for a house? These guards can be pricey because they don’t fk around. If price is an issue and you just need one for a house, maybe look into getting a roving person who can just patrol the house.