Can I buy WoW game time with Battlenet balance?

I'm curious to know if it's possible to use my Battlenet balance to purchase WoW game time. I've been playing the game for a while now and I'm running low on subscription time. I've heard that some players are able to use their Battlenet balance for in-game purchases, so I'm wondering if the same applies to game time subscriptions. Is this something that's possible, or do I need to use a different payment method to renew my subscription? I'd appreciate any clarification on this matter.