My question is can you connect to the internet? If you can supposedly you can use the FREE FB promo. May I ask what do you used to connect? Is it the browser or FB app?

For android users it should be automatic. If not,you may go to
Go to Settings > Wireless & Network > Mobile Networks > Access Point Names

APN : http.globe.com.ph (Prepaid)

          internet.globe.com.ph (Postpaid)
Username: -LEAVE BLANK-

Password: -LEAVE BLANK-

try to check the APN settings

PREPAID: http.globe.com.ph

POSTPAID: internet.globe.com.ph

hope it helps