Unfortunately, Apple does not allow for app developers to give out refunds–Apple handles all payment and refund transactions. They do so for a variety of reasons, but it's at their discretion. What you can do to set the refund process in motion is to get in touch with Apple directly, using the 'report a problem' option on the email receipt, or by following the steps outlined below:
1: Navigate to Apple’s Report a Problem page
2: Use the Apple ID used to purchase the subscription
3: Search for ‘Chordify’ and select ‘Report’ next to your subscription
4: Select the appropriate item from the ‘Choose Problem’ dropdown
5: In the text box, state that you’d like a refund and explain the reason
6: Click ‘Submit’
Please contact us at firstname.lastname@example.org if you need any further assistance.