I was charged on my credit card for an Apple.com Bill for an amount that does not show up in my purchases. How do I get help to get a refund or explanation.

This is primarily a user-to-user support forum; other Apple users like you. We don't have access to information about charges to your account. See each of the steps in the following instructions (in addition to what you've already checked). They include information on contacting Apple Support if the other steps don't help: If you see 'apple.com/bill' on your billing statement - Apple Support

I just went thru this. Make sure your Apple receipts matches the charges on your account. If they don’t and no one else uses your card, then cancel said card and make fraud disputes. Apple may or may not refund when you dispute the charge but credit card company would investigate and deal with them. Unfortunately I found out it was my daughter who used mine and I can’t get any money back.