Thanks for the response.
I ended up having to call the TG office in MNL - apparently the website isn't even supposed to allow you to buy tickets ex-MNL since Philippine law requires that you have to physically present the credit card... never mind that I've previously booked on their website. The whole thing is odd since other airlines (eg SQ, PR, 5J, DL) don't have this requirement.
Anyways long story short I ended up getting a Q-fare that only the MNL ticket office has access to since it's a "local" fare.