Mushi
A few tips for booking on Cebu Pacific which is not as easy as booking on CX or PAL. After trying numerous times, I phoned customer service and was told that the online booking only works if you have a Philippines credit card. However, customer service in Manila can assist you to book if you fax them a copy of your credit card plus a copy of the latest credit card statement. In the end, I thought it was easier to use a travel agent and found one on 3/F of World Wide House in Central (called El Sol). It cost around $80 more than if I had booked it myself online, but it was less hassle than faxing things.
If you are checking prices online, you need to check the international and domestic portions of the trip separately and then add the price up. I would suggest checking the price online first before you ask the travel agent because one of the travel agents I approached in Worldwide House gave me a price $1000 more than quoted online and kept insisting that the price fluctuates every minute. I just checked a few days ago and the fares to and from Manila around Christmas are around $2300 (including surcharges), but cheaper if she flies before 17 Dec. Good luck!