Unauthorized charges on credit card

Which card? For what type of thing?

The support article If you see 'apple.com/bill' on your billing statement - Apple Support explains how you can check your iTunes and App Stores purchase history, cancel subscriptions, and track possible sources of unrecognized Apple charges you may see on a bill. These may be purchases by Family Sharing members (you should see a receipt), others sharing your card (such as a spouse or a second Apple Account you have; you may not see a receipt). The article also provides a specific link for contacting Apple if you cannot trace the source of charges. If you use Apple Card you may find this document helpful too ➞ If you see an Apple Services charge you don't recognize on your Apple Card - Apple Support

Also note this service: View your App Store and iTunes Store purchases directly from your financial institution - Apple Support

"When you sign in to your financial institution website or mobile app and view your recent purchases from the App Store, iTunes Store, Apple Books, or for Apple Music or iCloud services, you may see an option—such as View Receipt—that allows you to view more details about your transaction."

Also contact the bank that issued your card.

If it is not apple, but some other company I would recommend that you contact that particular company