Give healers something called a "resource". Call it "mana" or something.
Whenever a healer casts spells - here's the big idea - IT COSTS MANA!
The resource ("mana" is just an example; it could be called anything) would then diminish as they cast their spells. If they don't have any resources left, they wouldn't be able to heal anymore.
I know it sounds like a strange idea to some, but if healers could only use their spells for a fixed amount of time, it would prevent them from running around in battlegrounds basically winning the entire BG for their team and never dying.
But, you're a hunter...
Why didn't you ice trap me?
Why are your pets not on me?
Why aren't you using Silencing Shot on me?
Why aren't you using the shot that stuns/disorients me?
Why isn't your Rogue friend kicking me?
Why is the Mage not using Counterspell and the ice stun thing?
Why isn't the Warlock fearing me? My Fear Ward is on a 2min CD, Dude!
Why isn't the Warrior Pummeling and Dragon Roaring and other such Warrior-ish things to me?
Why isn't the DK Strangulating me?
I could go on.
Do you play in a vacuum? No? Then you need to use your resources. The only thing I can do is hope to hold out 1 vs. 1. If you start playing smart, I'm toast.
Play smart. Win.