This support article is Recommended by Apple as the preferred source* of information for identifying payments you may see on a bill.
➜ If you see 'apple.com/bill' on your billing statement - Apple Support
"If you checked https://reportaproblem.apple.com and your emailed receipts and you're still not sure why you were charged, contact Apple Support" using this link --> https://getsupport.apple.com/?caller=ikb&PGF=PGF51002&category_id=SC0060&symptom_id=21084
Here's how to request a refund on an Apple mobile device (From: Request a refund for apps or content that you bought from Apple - Apple Support - see the article for more detail.)
1. Sign in to reportaproblem.apple.com.
2. Tap or click "I'd like to," then choose "Request a refund."
3. Choose the reason why you want a refund, then choose Next.
4. Choose the app, subscription, or other item, then choose Submit. If you were charged for a subscription that you no longer want, you can also cancel the subscription using the directions in this article --> If you want to cancel a subscription from Apple - Apple Support ].
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* I have a payment of $2.99 per month what … - Apple Community