The surgery on Don Hayden's son was successful. The only lingering complication: a bill for $23,000.

The Gaithersburg family, surprised that insurance didn't cover the cost, spent about a year fighting the charge from the medical clinic — even after it was reduced to $16,000.

The clinic turned the bill over to a collection agency, and the Haydens prepared to hire a lawyer.

That's when an administrative worker at the clinic advised the family in a whisper to contact Maryland's Health Education and Advocacy Unit, which mediates such disputes on behalf of consumers.

Investigators from the advocacy unit looked into the charge and found that the clinic had failed to submit claims in time to be paid by the insurer and so billed the patient instead. When the advocacy unit pointed out the error, the clinic agreed to forgive the bill.

The advocacy unit, Hayden says, is "probably the best-kept secret in town."

Indeed, many Marylanders are unfamiliar with this unit that is part of the Consumer Protection Division in the Maryland attorney general's office. But it's a resource to remember, particularly if you're confused by medical bills — who isn't? — or if your insurer always seems too quick to say no.

The advocacy unit assisted more than 1,900 consumers last year, recovering more than $1.2 million for them.

There are private companies that verify billing accuracy and negotiate medical bills on a patient's behalf, but they keep a percentage of the savings. The state's service is free.

Most states now have similar consumer-assistance programs, but Maryland's unit is one of the oldest and, some health specialists say, a model for others.

"They have a real solid history of success in helping consumers when their plan denies a service," says Cheryl Fish-Parcham, deputy director of health policy at the nonprofit Families USA.

When the Health Education and Advocacy Unit was established in 1986, its mission was to educate consumers and help them resolve disputes involving health care bills and medical equipment. In the late 1990s, it started assisting consumers as they challenged denials of coverage before insurance companies' appeals boards.

Now, thanks to the federal health care overhaul, the program is preparing for a heavier caseload.

"There is an expectation that when [the overhaul] goes into effect in 2014, that there will be 180,000 additional Marylanders insured," says Kim Cammarata, the unit's director. "Which means that there will be 180,000 additional Marylanders that may need assistance with insurance appeals."

The federal government gave the state a $642,000 grant last year to help with the extra work. Part of the money was used to hire two ombudsmen to handle appeals, for a total of five, and an outreach coordinator.

The unit aims to hire other staff, too, though managers will have to stretch those dollars. Unless more federal money is made available, Cammarata says, the grant will run out by the time the health care law takes full effect — and these added positions could disappear.

About 20 percent of the complaints the unit handled last year involved billing disputes. Sixty-three percent of those were resolved in the consumer's favor.

Most of the rest of the complaints were appeals of insurers' decisions to deny coverage of treatments that the companies deemed medically unnecessary, experimental or outside the contract.

The unit says it succeeded in getting 65 percent of the contract denials and 54 percent of the medical necessity denials overturned or modified last year.

(If consumers lose their internal appeal with the insurer, they can appeal to an outside agency or group. The Maryland Insurance Administration will hear appeals involving insurers it regulates. The advocacy unit will help consumers file appeals before the insurance administration, Cammarata says, but doesn't work on those cases.)

If you have a billing or coverage dispute, try resolving the issue yourself first. It might be possible to fix the problem with one phone call.

But if you're still confused or the matter is not resolved, Cammarata says, contact the advocacy unit.

"Sometimes the consumer is right; sometimes they're not," she says. "And sometimes they just need help understanding why they may not be right."

You can file a complaint online with the unit at http://www.oag.state.md.us/consumer/heau.htm. Or call 410-528-1840. You will have to submit a consent form that authorizes the unit to retrieve documents and talk to doctors and insurers on your behalf. You also should send along copies of your records — the more organized, the better.

"We will sometimes have somebody who will send in a paper bag with hundreds of documents," Cammarata says. "While we go through it, we are going to be a more effective and efficient advocate for you if it's sort of organized."

Consumers also can save money and headaches by understanding their coverage and making good decisions before seeking medical care.

For example, even if a hospital or doctor is in your insurance network, Cammarata says, the anesthesiologist or radiologist might not be, and you could get hit with a bigger bill than expected.

"In an emergency, you can't think about that," she says, but if you are having elective surgery, you can request medical personnel that are covered under your plan.

Also, more consumers are surprised to see on their bill a "facility fee" that can run $100 when they visit a doctor's private office that is considered part of a hospital, says Adrian Redd, a unit ombudsman. Ask about the fee before your visit, she says, and avoid it by choosing a health care provider that doesn't charge one.

Holly Carbone, 62, of Ocean Pines says she understood her rights under her policy but still needed the help of the advocacy unit. She suffered severe stomach pains that sent her to the emergency room twice last year and led to a series of tests to uncover the cause.

She says she figured insurance would pick up the tab because she had already met the $3,000 deductible — and had the paperwork to prove it. But the insurer contended that the deductible hadn't been reached, and it wouldn't pay the bills of the doctor and hospital that treated Carbone.

The battle between patient and insurer dragged on for months.

"I became of the firm opinion that everyone at insurance companies is told to say, 'Deny, deny, deny,' as many times as you can," Carbone says.

But after Carbone contacted the advocacy unit, the matter was settled within weeks. The insurer agreed to pay.

If it hadn't been for the unit's help, Carbone says, she might still be fighting her insurer.

"Let's face it," she says. "Even if you're an insurance company, if you get something on the letterhead of the state attorney general's office, it tends to make you want to pay attention."