Actually you can contact C&B directly, however you need to do it during Britian's business hours, and be prepared to speak to someone on the phone...also, it may take you a while to get in touch with someone directly...it literally took me two weeks. It was insane. When I did get in touch with someone they were rude to me when I was being nice.
Also, anyone looking to cancel their C&B accounts are better off canceling their current card and getting a new one issued by your bank. Because like many have said, they keep your information on file, some have mentioned they re-activate accounts and start charging, and if you do go through with canceling them on your current card you will be jumping through hoops of fire blindfolded while people are tossing eggs at you...just sayin'