Hello connallyH,
Carefully read and follow ALL the steps in the first link below. It tells you how you can check your purchase history, cancel subscriptions, and track possible sources of mysterious "iTunes" charges you may see on a card, particularly those from family members if you are an organizer of a Family Sharing group. It also provides a specific link for contacting Apple if you cannot trace the source of charges.
Click on this link taking you to a document titled: 'If you see ‘itunes.com/bill‘ or an unfamiliar charge on your bank, credit card, or debit statement' --> https://support.apple.com/HT201382 If after trying all the methods described in the article and after contacting Apple Support in item 5 you do not see charge anywhere other than on a card that you alone control, contact your financial institution. Both you and Apple may have been the victim of card fraud.
If you now recognize this purchase and are asking for a refund then realize Apple's terms of purchase for most countries are effectively, "All Transactions are final" (check terms at: https://www.apple.com/legal/internet-services/itunes/us/terms.html ). Apple does refund on a case by case basis, but they can also refuse.
Read this document to 'Request a refund for apps or content that you bought from Apple' --> https://support.apple.com/HT204084
Click on this link to proceed directly to 'Report a Problem' for requesting a refund --> https://reportaproblem.apple.com/?s=6
If a reporting a problem request is unsuccessful you can also try clicking here --> https://support.apple.com/choose-country-region/media-services Select your country, then a product.