(MONEY Magazine) – Q Someone stole my credit card and charged Walt Disney World tickets. I reported the fraud to American Express. They said they'd look into it but never did. Now my account is in collections! To say that I'm fuming with outrage would be putting it mildly. --T. Turner, Marietta, Ga.

Answer You did everything right, almost. You scanned your bill, spotted the error, and contacted AmEx within 60 days, the window that credit-card companies must leave open for reporting customer complaints. But even after several calls and a letter, AmEx didn't respond. (They're supposed to, in writing.) Corporate juggernauts do make mistakes.

Because the company didn't have a record of your request for an investigation, your account appeared to be delinquent. They canceled your card and sent your account to a collection agency. When you finally got someone on the phone, you were told the charge wasn't even fraudulent. Adding insult to an increasingly ugly injury, AmEx insisted that you had passed the 60-day notification window, so there was nothing they could do.

You had a copy of your letter, but no proof it was received. A big lesson about dealing with a corporate big boy: Certify your mail.

By some freak of red-tape circumstance, you did have an odd form of evidence: a copy of the ticket order, which you had tracked down from Walt Disney directly. Not only did it contain someone else's name and address--clearly marking it as fraud--but it contained the notation "CC dispute," stamped with a date that fell within the allotted 60-day dispute window. Ha!

Evidently someone in the AmEx machine had started, but not finished, checking out your case. We got AmEx to take a second look at your order and that seemed to crank up the customer service machine again. Within days, AmEx reversed the fraudulent charge of $3,188.88 and the additional delinquency charges of $583.06.

Having an advocate like us step in was lucky for you. But if you had used certified mail in the first place, the whole problem would have been avoided. One last thing: During all this, you neglected to pay $308.21 in legit charges. Not good. A dispute investigation doesn't put your whole account on ice.

TIP

A phone call is just a cry in the dark. Refute fraudulent charges in a letter sent via certified mail with return receipt. Keep a record of all follow-ups--dates, phone calls and actions taken.

Having a financial nightmare? Need an advocate or some good advice? E-mail Ellen McGirt at money_helps@moneymail.com.

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Reporting By Kate Ashford contributed to this article.