Rob makes the point about credit card mandates. If you read the small print about credit card "standing orders" you will see that your contract is with the end company that you are paying, not the credit card firm. The card issuer will continue to deduct money from you and pay it to the company concerned so long as that company state that they have a contract with you. You can chop your card up and attempt to close the account but your credit card company will continue to rack up the charges (including interest). There have even been cases of County Court Judgements being awarded without the debtors knowledge simply as a result of "standing order" failures.
By far the safest way to make regular payments is Direct Debit mandates from your bank account. You are in complete control of them and you can stop them at any time without penalty. With online banking you can create and delete them at will.