Let's find out where the charge is coming from, mdoba.
I've checked and found no investigation about the unauthorized charge in QuickBooks.
Your client can check if someone is using their credit card for online payments. You can use the lookup charge tool to find out where it's coming from and why. Here's the link: Understand Intuit charges on your credit card or bank statement.
If the charge is coming from us, I recommend contacting our QuickBooks Merchant Team. They can trace the payment and process refunds when needed.
Please use this link to get in touch with them: Contact Payments.
Let me know how the contact goes by leaving a comment below. I'll be right here whenever you have follow-up questions about your billing charges.