Very good question and frankly, I was somewhat in the same boat in the Philippines. I did it electronically using I forget what I used, and I couldn't tell you how I did it again. Normally, I buy my tickets at our pass office, but I found that you can do this using a computer which I had.....A LAPTOP...no, rather a NETBOOK type of miniture laptop and somehow managed to buy a pair of ANA tickets that way. I totally forgot how I did it now. I normally try to stick with my airline when travelling, or if not, I try to use the pass office to buy tickets, but sometimes, when the flights get full as you say, that is when the unknown factor results, especially when you haven't done it in a while.