Here to share my experience, i got hacked way back in 2009, but not the authenticator type of hack, i email them, and in get back everything in a few days time.

Imo, email is the best way to go. It all depends on how u write your mail. Just be courteous, detail and straight to the point. I don't even need to tell them my Cdkey. Very fruitful experience for me, not like i want to get hacked again, but i believe in their efficiency.

I thought can use mobile authenticator, which is free?

But now since, i started playing in wow taiwan, only i realize i cant use authenticator here. Finger cross.

Just be alert all the time, and you will minimize the risk of getting hack.