[Google Play]
Please read this article:
https://support.google.com/googleplay/answer/2851610

If your issue is not resolved, please contact Google Play support:
https://support.google.com/googleplay/gethelp

[iOS App store]
Please read this article:
https://support.apple.com/en-us/HT201382

If your issue is not resolved, please contact Apple support:
https://getsupport.apple.com/