The revocation procedure depends on your booking variant:
Apple:
- Go to reportaproblem.apple.com.
- Log in with your Apple ID and password.
- When you see the "Report" or "Report Problem" button next to the item you want to request a refund for, click it.
- Follow the instructions on the page to select a reason for the refund and submit your request.
Google:
- Go to the play.google.com/store/account page.
- Click Order History.
- Find the order you want to return
- Select "Request a refund" or "Report a problem" in the order.
- Select the option that best describes the situation.
- Fill out the form and note that you want a refund.