If your account is already closed, you will be directed to the account management website (http://accounts.eamythic.com) when you log onto the game.  Simply login to the site, click on the Activate button for the correct product account, and enter your billing details as prompted.  If the transaction is approved, your account will re-open.

If you are in the middle of a subscription period, and you wish to reverse a cancellation request that you made through the game interface, or by contacting support, you would simply need to update your billing details.  By updating your billing details, you can avoid any interruption to your service.

If you need guidance on how to update your billing details, please refer to the following KB article: http://support.darkageofcamelot.com/kb/article.php?id=910