Only through refund requests can refunds be approved. There is no appeal procedure for the staff decision. In principle, all sales are final, with exceptions on a case-by-case basis. Could it be that this has happened repeatedly in the past?
Refund requests have a time limit. Could it be that it was too long ago? There is a few weeks delay before the app developer gets paid. After that has been done, then refunds are no longer possible.
If you give your device to others, then please set your devise for requiring the password for all purchases, to prevent unwanted purchases.
- Settings﹥Screen Time﹥Content & Privacy Restrictions﹥Content & Privacy Restrictions
﹥iTunes & App Store Purchases﹥ʀᴇǫᴜɪʀᴇ ᴘᴀssᴡᴏʀᴅ﹥Always Require.