I am having the same login issue , I also downloaded a client to get in and when I try to login I get 
The information you have entered is not valid. please check the spelling of your account name and password . if you need help retrieving a lost or stolen password and account , see 
www.worldofwarcraft.com for more information 
 to my experience this is usually caused by an incorrect realmlist 
my realmlist at the moment is 
set realmlist 178.33.122.86:3725
so wondering if anyone can help