Cancelled my subscription, now how do I get refund?

I downloaded an app and authorized a 3 day free trial of the extra features, but wasn't happy with the app overall or the additional features and deleted it that same day. I checked my credit card after the trial period had ended to make sure I didn't get charged but I did, so I figured out how to manage my subscriptions and cancelled it. Who do I get in touch with to get my money back? (its over $100 because the subscription would have been on a yearly basis not monthly)