Sounds like a trick out of the AOL or NETZERO playbook.
After several attempts at getting them to stop, here's a trick I used to stop it: I changed "method of payment" to a paypal debit card account with NO FUNDS in the account. You could use a prepaid card with a dollar left on it to do the same. HULU will check to see that it's a valid card, but when they try to debit your monthly fee, there will be insufficient funds.
This shouldn’t be happening and they can’t it must be an error. I would contact both Hulu Plus over the phone, and your credit card company. Hulu Plus if you explain the situation should be able to refund you your money if you can prove and explain what happened.
Contact hulu billing support if they do not take care of it. Contact your credit card company. Keep record of the emails on any tickets you send to Hulu. Shocked hulu doing this intentionally as it is not that hard to dispute it with your credit card company when you are credit back the money the merchant account not only takes money back from the account, but generally charged around a 45 dollar fee. To many disputes and the fee goes up from their.