A few years ago I booked a flight home through HIS travel and they let me split the payments across 2 different months (flight was in Dec., booking day was in October) but I've heard unconfirmed rumours that this practice has gone out the window/that the payment period is separated by like a week.

Does anyone know of any agencies where I can book a round-trip ticket, pay half one month then half the next? I'd like to book my Xmas flight home by next month if possible.