It's a good idea to check your purchase history first to verify what the charge is for:
View your purchase history for the App Store, iTunes Store and other Apple media services – Apple Support (AU)
If you can't find this charge in your purchase history, you may have another Apple ID where the charge can be located. It is also possible that you may have allowed your payment card to be used by another Apple ID. If you have a family sharing set up, the charge can also come from one of the members
Please Contact - Official Apple Support so they can further investigate this