Please get in touch with our support team using the in-game Customer Service feature or via the chat icon at the bottom of the atricle on https://monopolygo.helpshift.com

When contacting support, please provide a screenshot of your purchase receipt to assist with your request.
To locate your purchase receipt, follow these steps:
1. Visit http://pay.google.com/ and sign in with your Google account.
2. Tap "Activity" which is located at the top of the screen.
3. Select your order to see the detailed receipt.
Please make sure that your Transaction ID (starting with "GPA") is clearly visible in your screenshot.

 Google Play Store Invoice