Sometimes your card will be charged even if the process fails. In my case this kind of error will be automatically corrected in week and this miss-charge disappears from your bank account (Its more like reserve till the end of month). If its there next week I would be worried thou.
Don't get me wrong I'm not trying to defend SE or anyone else. This kind of issues has happened to me in every goddam mmo and I've had to try correct it each time.