If neither you nor your child have played the game, and you suspect that someone has obtained access to your account, contact Apple (for iOS devices), Google (for Android devices), Samsung (if you have downloaded the game from Samsung Galaxy Apps), Windows, or the social network through which the payment has been made right away.
For Apple devices
Go to tech support, and select Contact iTunes Store Support. Then select Purchases, invoices and refunds, and find a situation that most closely matches yours .

For Google devices (Android)
Go to tech support, and select Contact us. Shortly after that, Google tech support staff will contact you via your preferred method of communication. If you have already contacted the correct organization, and they have forwarded you back to us, please contact us by pressing the button in the upper-right corner, making sure to include all relevant information: time and description of what has occurred, ID of your transactions, relevant screenshots, and any other information that you believe will help explain your situation. We will do our best to help you.

For Samsung devices:
  • Navigate to Galaxy Apps.
  • Open the menu (drop down menu to the right of the search field).
  • Press Contact us.
  • On the page that appears, press Ask a question, describe the problem and press Send.
For Windows Phone devices (Windows Mobile):
Go to tech support, and select Start. In the window that appears describe your problem.

Facebook:
If funds were withdrawn from your account and you are not sure why, take a look at your purchase history. If after looking at your purchase history you still do not understand why the funds have been withdrawn, contact support.