A minor in my family buying something from app store without my permission

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If Apple has notified you that it is not eligible then so be it.

We can't help you, sorry, we are also users of Apple products & services like you. 

A minor in my family buying something from app store without my permission

To avoid such a case in the future, see ⤵️

Require a password for App Store and iTunes purchases

Require a password for App Store and iTunes purchases - Apple Support

Manage App Store purchases, subscriptions, settings, and restrictions on iPhone

Manage App Store purchases, subscriptions, settings, and restrictions on iPhone – Apple Support (UK)

Prevent in-app purchases from the App Store

Prevent in-app purchases from the App Store – Apple Support (UK)

There is one other option.

Call Apple and when the 1st tier agent answers the phone, politely but firmly request that your call be expedited to Customer Relations. Don't discuss your issue with anyone except CR.

PS - Any minor who has access to making purchases on your account, has your permission.

M1 Mac mini, macOS 13.2; Watch, series 7 GPS/cellular, watchOS 9.3; iPad Pro 2nd Gen, iPadOS 16.3; iPhone 12 Pro, iOS 16.3; TV 4th Gen, tvOS 16.3.1; HomePods, audioOS 16.3.1 and Airport Express w/ Airplay 2