If your payment was not processed properly due to technical issues and no Coins were added to your account, you will not actually be charged because your payment was not processed completely.
If the payment has not been canceled or refunded, please contact your original point of purchase (Google Play Store, Apple App Store, or 3rd party payment body) and file a refund request if needed so.
Restarting the WEBTOON App after a few minutes after the purchase would help verify if the Coins purchased will reflect on your "Coin Shop" page. Please get in touch with our Community Support team for more help.