What Happens If: You scream at the rep.

What the Experts Say: Nearly everyone has had the urge to yell at an unhelpful customer-service agent, but our panelists say that’s a big mistake. If you yell or curse, you’ll probably be put on hold. And despite what she may say, the rep probably isn’t making you wait so she can check with her supervisor or read her policy handbook. “Sometimes, rather than pressing Hold, we press Mute,” Morrill says. That way, you can’t hear the rep, but she can still hear you muttering and sighing on the other end of the line. “Some reps will just take a 10-minute coffee break or play on the computer for a while,” she says. Whatever yours is doing, there’s a good chance she’ll keep doing it until you get tired of waiting and hang up.

Remember: Reps typically don’t feel they have any stake in customers’ happiness — or even the success of the company. “They’re overworked, and they’re dealing with problems that they didn’t cause all day long,” says Katherine Harris, a former phone rep for a mail-order food company who is now a professor of marketing at Babson College, in Wellesley, Massachusetts. “If you yell at them, it’s only human nature for them to clam up and become less helpful.” A vindictive rep can even retaliate against a screamer. “In some cases, she will be able to change data about your previous transactions, dates when you called, or things that you have been promised,” says Diane Graden, a customer-service consultant and a 32-year veteran of airline customer service who operates a small call center in Austin, Texas.

Bottom Line: Don’t yell. If you’re dealing with a rep who is particularly infuriating or is playing hardball, the best thing to do is end the conversation as graciously as you can, then call back and start over again. “There are possibly thousands of agents, and each one has a different level of skill, caring, and follow-through,” Dawn Hampton says. “Hopefully you’ll get someone better the next time.”

What Happens If: You threaten to take your business elsewhere.

What the Experts Say: Except with small companies (or the rare big one with an exceptional customer-service department), this kind of threat will get you nowhere. Despite the old business credo that the customer is always right, customer-service departments tend to operate on a herd mentality. “The attitude of the company I worked for was to move customers off the phones like cattle,” Williams says. Pleasing the callers isn’t the mission — getting rid of them is. “Losing one customer won’t do much damage to a big company,” Knight says. “Even if you convince 10 of your friends not to patronize it either, that really isn’t going to have an effect on the profits.”

Bottom Line: Don’t waste your breath.