Unauthorized charge to my VISA card

Read the last line of my post. We cannot do anything for you, we can only tell you how to proceed to do this for yourself.

Follow the instructions in the links in my post.

Do not include your email or information in your posts that you do not want the world to see, unless you like receiving spam.

You do not say where you see this purchase. If it is an e-mail are you sure it is real and not an attempt to steal your private information ('phishing') (very common)?

Phishing & Other Suspicious Emails - https://www.apple.com/legal/more-resources/phishing/

Identifying legitimate emails from the iTunes Store - http://support.apple.com/kb/HT2075 (the previous link is more specific)

Forward attempts to: reportphishing@apple.com

If you still think the charge is real:

See your purchase history in the iTunes Store on a Mac or PC - http://support.apple.com/HT204088 - Does not include purchases made by others under Family Sharing; those have to be checked from their accounts.

If you see ‘itunes.com/bill‘ or an unfamiliar charge on your bank, credit card, or debit statement - https://support.apple.com/HT201382 - "Before you contact Apple to request a refund for a charge you don't recognize"...

If neither you nor a family member (if applicable) has a record of this purchase and you only saw it on a statement for a credit card you alone control, contact your bank or card company about card fraud. Apple does not handle that.

If you recognize this purchase and are asking for a refund then realize Apple's terms of purchase in the USA are, "All Transactions are final" (https://www.apple.com/legal/internet-services/itunes/us/terms.html), but some countries have different laws so check terms for your country at: http://www.apple.com/legal/internet-services/itunes/. If sales are final then it is Apple's decision if they want to grant a refund. You can always ask, and people do get refunds on a case by case basis, but Apple can also say no.

Get help with an item purchased from the App Store, iTunes Store, or iBooks Store - https://support.apple.com/HT204084

Report a Problem - http://reportaproblem.apple.com - "Sign In for help with iTunes purchases made in the last 90 days"

Other ways to contact iTunes Support:

https://support.apple.com/contact

https://www.apple.com/emea/support/itunes/contact.html

You have posted in a voluntary, user-based, technical support community - it is very unlikely Apple will respond to, or even read, your post here, only other users like yourself.