When contacting HP reservations, I'd recommend using the little "HP Online Chat" function that's found in the left sidebar, instead of calling.

In my experience, the chat works fantastic. It's very quick, very easy, there's almost never any waiting, very friendly agents handle your requests and they get done what you need done ASAP. Whether it's upgrades, fare information, whatever... they'll handle it.

It's a very innovative feature that HP should be applauded for.