Contract law in general does not prescribe that the contract is automatically terminated with no obligations if some payment doesn't arrive. The method of paym

Contract law in general does not prescribe that the contract is automatically terminated with no obligations if some payment doesn't arrive. The method of payment is pretty much orthogonal to any obligation to pay and the continuation of the contract. The contract may stipulate that the merchant is free to cancel the subscription if you don't pay for whatever reason (the card expires, the card does not have money, you chose to pay in cash and didn't have a card, whatever). However, the contract can (and usually does) stipulate that the merchant is not required to cancel the subscription in case of non-payment, and in that case the contract is valid, they owe you service and you owe them the contractually agreed payment. On the other hand, contract law generally would assume that the subscription is cancelled if you sent them an unambiguous request in writing even if their standard process flow (e.g. requiring a phone call with a sales rep convincing you not to quite) wasn't followed - if you've sent a letter than that and stopped paying, that should be appropriate in most circumstances.