I've had my account banned for several months now, untill I got aware of this bug on the forums:
Go to the forums (duh).
WoW Forums ->
When you normally try to log on,
You get an announcement you have been banned and cannot post anymore on that account.
However, if you select another localisation (either fr, en, de, es and soon ru)
And go to one of those pages (with everything writen in the other language of your choice)
You can log on. You will be asked to select on of your characters to post on. Select the correct one and you will be returned to the previous page.
Then simply select the EN version again
and you can start posting again!
NOTE: This only works for EU accounts since the US has no localisations next to the english version.