(MONEY Magazine) – Lately, some credit-card issuers have been making it tough for customers to dispute unauthorized charges on their bills. The Federal Trade Commission, for example, has recently filed a lawsuit against Dillard Department Stores for allegedly requiring customers to file notarized affidavits, among other things, before the Little Rock-based retailer would investigate cardholders' claims that their charge cards had been used without their consent. Salem, Va.-based Bankcard Holders of America says it has received complaints from other consumers who were forced to testify in court before plastic issuers would investigate reports of illicit charges.

Consumer advocates contend that such hassles will discourage cardholders--who every year are billed a collective $1.1 billion in fraudulent charges--from questioning their bills. Says David Medine, associate director for credit practices at the FTC: "Consumers should not face obstacles to getting unauthorized charges taken off their account."

The Federal Reserve Board is now pushing for tougher standards in credit regulations to prevent issuers from imposing unduly harsh conditions on cardholders. But even if that effort is successful, lenders would still have until October to comply. Meanwhile, here's what to do if you think your card statement may contain an unauthorized charge:

Call the card issuer immediately. As soon as you realize that your credit card has been used without your consent--or better yet, as soon as you find it missing--telephone the bank or department store and explain what happened. Once you do that, the Truth in Lending Act requires the card issuer to investigate the contested charges. The bank or retailer may ask you for information such as the date you lost your card and whether you filed a police report. You may choose to cooperate in any investigation to find out who used your card, but the card issuer cannot deny your claim solely because you choose not to. In any case, you cannot be held liable for more than $50 in false charges--and you cannot be forced to pay any charges made after you report the card missing.

Put your complaint in writing. Although you are under no legal obligation to do so, writing a letter to the card issuer specifying the disputed charges could speed up the resolution of the matter, says Federal Reserve senior attorney John Wood. Reason: If you write within 60 days of a bogus charge appearing on your bill, the issuer is required by law to reply in 30 days and resolve the issue within 90 days of your letter. If you don't write, the card issuer is under no deadline, and the matter could drag on indefinitely. If the issuer doesn't respond or fails to resolve the matter within three months of getting your letter, it has to deduct the first $50 of charges from your bill, whether the charges were authorized or not.

Report the card issuer. If the credit- or charge-card company refuses to investigate the misuse of your card unless you file a police report or fulfill some other requirement, tell the issuer you will complain to your attorney general's consumer affairs office, the Federal Trade Commission in Washington, D.C. (202-326-3758) and, in the case of a bank credit card, state or federal banking regulators. (Which regulator to get in touch with depends on whether the bank is chartered by the state or the U.S.; call your bank to learn the appropriate agency.) Chances are, once you show that you're ready to fight for your rights, the card issuer will honor them.

--Susan Berger