You don't have to cancel your card. Just contact the company (online or phone or mail) and tell them you do not wish to extend your subscription, and they will stop it and refund any money for the automatically extended subscription. At least that's what legit magazines do. This number is calling me, too.....several times a day....my caller id says, "Pennsylvania". Very irritating.
Called at 4:23 am on a Sunday morning. Pre recorded message that my prepaid card expired. No idea what card they are talking about because I have no prepaid ones.