Refund

Did you subscribe on their website or through the Apple Store. If it was on their website you will have to get it through them.

If from Apple: View, change, or cancel your subscriptions - Apple Support

If you are past the deadline date for cancelling you owe whatever you paid and won't get a refund.

See this for cancelling subscriptions, View, change, or cancel your subscriptions - Apple Support

Then see this about a refund, Request a refund for an App Store or iTunes Store purchase - Apple Support