I accidentally made a purchase with a Google Play coupon credit. How do I receive a refund for my Google Play credit?

For issues related to Google Play credits, you will need to contact the Google Play store directly for assistance in reinstating your credit.

To contact Google Play, please visit the link below:
https://support.google.com/googleplay/answer/6179357

For additional information about Google Play refunds, please visit:

https://support.google.com/googleplay/answer/2479637#apps&zippy=%2Capps-games-in-app-purchases-including-subscriptions