#2 - Sept. 4, 2010, 6:29 a.m.
As Eilethalua suggested, it may be most wise for your friend to contact Billing as soon as they are able to, and preferably by phone. However, in the mean time, they should review this information:
Account Hacked? Security Issue? Look Here!
http://forums.worldofwarcraft.com/thread.html?topicId=24702231244&sid=1
Battle.net Account Security Awareness
http://us.battle.net/security/
Account and Computer Security
http://us.blizzard.com/support/article/30794
Battle.net Authenticator
http://us.blizzard.com/support/article/24986
If you like, you can also submit an in-game petition yourself reporting this situation. Just make sure to include the name and realm of a character on your friend's account so that our Game Masters are able to locate the proper account. This way, they can see if there was any gold or item losses and begin the restoration process. =)