How to avoid automatic subscription renewal

As most of us know, WoW credit card subscription plans in the US and Europe are auto-renewing. If I sign up for one month at $14.99, as soon as that month is up, Blizzard immediately re-bills my credit card and signs me up for another month. This is problematic for some people, who may want to switch to a game card at the end of the month, or who simply might not want their cards to be