Dispute a credit card billing error in writing within 60 days
Added
If a holiday order never arrives or you're charged the wrong amount, call your card company, then send a written notice to the billing-dispute address on your statement. Keep a copy, and keep paying the charges that aren't in dispute.
The result
Result: CFPB: send written notice no later than 60 days after the statement with the error; the card company has 30 days to acknowledge it and two more billing cycles to investigate, and you don't have to pay the disputed amount while it does.
Source
Consumer Financial Protection Bureau: How to fix mistakes in your credit card bill (opens the original source in a new tab). Check it for the latest numbers before you act.