If you registered through the iOS app on an iPhone/iPad, your subscription is held through Apple. While DIY does not have access to cancel or refund an Apple subscription, you'll need to contact the iTunes Support team who can view your subscription and verify all options for a refund.
Apple US 800-275-2273
Apple Canada 800-263-3394
Apple UK 0800 107 6285
Apple Australia (61) 1-300-321-456