Squeakers, the Trickster

I know Blizzard Entertainment is very clear that you cannot use battlenet balance in purchasing subscriptions. Squeakers, the Trickster is tied to purchasing a 6-month subscription, but not 6 months of game-time. Why is that? Why not both? I received Battlenet gift cards for the holidays and wish to purchase my new subscription to World of Warcraft, but cannot. I must purchase game time and in doing so, lose out on Squeakers, the Trickster. Any solution or work around for this? Like changing my battlenet currency into paypal or something?