I want to make full refund

See here - Request a refund for apps or content that you bought from Apple - Apple Support

Your refund request may still be processing. Try checking its status-

1. Go to reportaproblem.apple.com and sign in with your Apple ID.
2. Choose Check Status of Claims. If you don't see Check Status of Claims, you don't have any pending refund requests.
3. To see the status, tap or click Pending.

Also, funds may take a while to appear, depending on your payment method-

Store credit - It might take up to 48 hours to see the refund in your Apple Account balance.

Mobile phone billing - It might take up to 60 days for the statement to show the refund. Processing time might be affected by your carrier. You can contact your carrier for an update.

All other payment methods - It might take up to 30 days for the statement to show the refund. If you don't see the refund after 30 days, contact your financial institution.

However, if your refund was denied, there isn't much you can do about it. Refunds for services are generally the exception rather than the rule.

If you'd like to take this up with Apple Support, though, it may be worth a shot. Go to this page, then click "Billing and Subscriptions", then "Request a Refund".