We are aware that many of our Russian speaking players, European account owners, upgrading to World of Warcraft: Wrath of the Lich King have purchased the retail boxes that only work with Russian accounts. Therefore, we have decided to make the European to Russian account conversion process available again until 16 December (inclusive). However players that would like to keep their European accounts will be able to contact our Billing team to arrange this. For all the details, please refer to the forums.
You should transfer your characters before converting your account. Thus, the free character migration from European to Russian realms has also been extended until 16 December. Please check our character migration FAQ for further information.