I am trying to book flights for us, from Ottawa to LAX, on March 7 - on the cheapest upgradeable fare. The telephone AC reservations agent stated that a V class fare requires a 14 day advance purchase, while an H, Q, and L fare require only a 7 day advance purchase.

I always thought that a V class fare can be purchased 7, rather than 14 days in advance - for domestic, transborder, and international routes (of course, V class fare is not upgradeable, except on transborder routes).