Suppose an individual is subscribed to a service that costs $3.00 per day. He uses his credit card to pay for this service. Also, suppose this individual wants to cancel his subscription but has forgotten his username and password for this service. He has tried contacting the merchant, but the merchant cannot locate his profile. What should this person do if doesn't want to keep being charged $3.00 per day?
A vendor accepting/taking ongoing payments should have the ability to find an account given the card number. Of course "should" doesn't always result in that actually happening.
The next step is to contact the card issuer, and give them the exact details. While I realize that one may have legitimate recurring billings on their card, this is the risk they take, that they may need to cancel the card and re-enter the new account with the other service providers. To be clear, the answer here is "you may need to cancel the card", but only after consulting with the issuer, and only as a last resort. They should be able/willing to block further charges.
but the merchant cannot locate his profile
I'd say that's a justifiable reason to get your CC to reject new charges. Don't try to be evasive and cancel your credit card because if you stop paying attention to it then it can continue racking up charges from existing contracts.
If you were on a contract, 12 months for example, then the merchant can easily prove that these charges were agreed to by you.
Hopefully this means that the merchant got off their a$$ and located your profile so go ahead and re-contact the merchant.
This is obviously a sort of recurring payment and can be accumulated to a big amount, if not stopped. Even if the subscription is been stopped, the payment continues to get credited to the service provider's account. It will not be a deliberate case, the service provider, from where the subscriptions were made will not give any sort of attention to this. it is the sole responsibility of the cardholder to stop the payment.
In the case of the United States, Federal law provides enough provisions legally to withdraw your consent and you can put a halt to the recurring credit card-based payment. You can contact your card issuer over mail or phone or even by letter. After giving the stop payment order, you can observe your bank account transactions and make sure the payment from that credit card has been stopped for that particular merchant. In my limited knowledge, I don't think you have to cancel your credit card for this issue.