You’re a smart consumer. You hold onto your receipts, and you review your credit card statement carefully every month like you’re supposed to. For the most part everything goes smoothly. Your records match those of your credit card company, and you know exactly where your money is going.

One day, things go horribly wrong. You review your credit card statement. You see a charge (or if you’re very unlucky, a few of them) that you don’t recognise.

“Wait a minute,” you say. “I know I didn’t authorise this charge!”

Uh oh. What do you do now? It’s time to dispute those charges on your credit card.

Credit Card Disputes: Start With the Merchant

Before you contact your credit card company, the first step should be to contact any merchants that put through charges that you believe were not authorised. If there was an honest mistake (like a technical glitch that put through a single charge twice), they should be able and willing to reverse that charge for you quickly.

In other cases you’ll find that the mistake was on your end. Maybe you forgot about a purchase, or a store’s corporate name showing up on the statement looks a bit different than the name you know them by, so you were confused. Or perhaps you agreed to a contract with auto-renew billing and you forgot about it. In that case, you did in fact authorise the charge and the company doesn’t have to reverse it (unless they have a money back guarantee or some other refund policy in place that you’re still eligible for).

Every now and then you’ll come across an unhelpful merchant even when a charge truly wasn’t authorised. Perhaps the charge looks legitimate on their end, but it turns out your card is missing and you think you were a victim of credit card fraud. In that case it’s time to contact your credit card company.

Dispute a Charge With Your Credit Card Company

Pick up the phone and call your credit card company. Right away. If your credit card is missing, let them know the last time you saw it, that it is either lost or stolen, and that you believe it’s being used to make unauthorised charges. Have the account shut down immediately so a credit card thief can’t use it any longer. You’ll be able to get a new card.

Your credit card company might have special phone numbers for reporting lost or stolen cards or disputing charges. This might be on the card itself. Write it down somewhere safe (since you obviously won’t have the card on-hand if it’s missing). If you don’t notify your credit card company quickly, you might be liable for those unauthorised charges because you were negligent and allowed them to continue.

Each credit card company might have slightly different procedures for reporting unauthorised transactions. If you use a Citibank credit card for example, they have a formal dispute process where you need to fill out and fax them a dispute investigation request form. Always make sure you’re aware of the dispute resolution process with your own credit card company.