Apple Service charges - from "unknown Apple ID"

We had numerous charges come through PayPal (14 charges over a 2 week span) reflecting as paid to Apple Services. Apple support could not find them under my Apple ID but once I gave them the invoice number they said it came from a different Apple ID. (Do not have any family members sharing). They will not disclose this ID information, or which vendor was ultimately paid citing privacy issues. They denied our refund request as did PayPal who informed us that ultimately we need to take it up directly with Apple. Any suggestions on how to proceed?