It’s not just who gets your letter that matters — it’s who else gets it.

Here’s a rundown of whom to copy.

Airline complaints should be copied to the Department of Transportation’s Aviation Consumer Protection Division.

Here’s the address:

Aviation Consumer Protection Division, C-75
U.S. Department of Transportation
400 7th Street, S.W.
Washington, D.C. 20590
Here’s how to contact the DOT

Note: This is the contact information for informal complaints. Here’s where to file a formal complaint.

Car rental complaints should be copied to the state attorney general in the state your rented the car in (not your home state) and, if it involves a questionable insurance claim, that state’s insurance commissioner. A list of attorney generals is available from the National Association of Attorneys General Web site. A list of state insurance commissioners can be downloaded here.

If your complaint is about a hotel, you can also copy the attorney general if the state in which the hotel is located.

Got a problem with a travel agent? Many agents are members of the American Society of Travel Agents, which will investigate ethics complaints.

American Society of Travel Agents
1101 King Street, Ste. 200
Alexandria, VA 22314

If you feel as if you’re the victim of an agent’s bait-and-switch or some other form of dishonest advertising, copy the Federal Trade Commission.

Federal Trade Commission
CRC-240
Washington, D.C. 20580

If you had a problem on a cruise, copy the Federal Maritime Commission, which can sometimes mediate disputes on your behalf.

The Federal Maritime Commission
800 North Capitol St. NW
Washington, DC 20573
complaints@fmc.gov

If your complaint involves a sanitation issue on a cruise ship, copy the Centers for Disease Control and Prevention.

Centers for Disease Control and Prevention
1600 Clifton Rd.
Atlanta, GA 30333

P.S.: If you get a “no” after your first round of letters, don’t worry. During your appeal, here are two more people to copy.

» Your family lawyer.

» Me. You can e-mail me here.