Credit: ABC News

Irene Azzollini was relieved when doctors were able to reattach her son's middle finger after he chopped it off in a freak accident, but the insurance company error that resulted in a $10,000 out-of-pocket bill left her feeling nothing but stressed and defeated.

"I wasn't aware of the charges," the boy's mom, Irene Azzollini of Millbrae, Calif., said. "At no time did the surgeon or the hospital or the nurses say anything like, 'She's not in your network.'"

Lucas Gonzalez, 12, was on his way to camp one morning in July when he grabbed a heavy door by the outside edge and slammed it behind him. He didn't get his finger out of the way in time, and severed it from the knuckle, severing the bone, two nerves and two arteries in the process.

While Azzollini, 45, put the severed finger on ice, her husband stopped the bleeding. At 8:18 a.m., he hadn't left yet for his job as a paramedic.

They went to Mills Peninsula Medical Center in San Francisco, where Lucas spent three hours in emergency surgery to have his finger reattached. Today, he's returned to almost full mobility.

"The doctor was an amazing, fabulous surgeon," Azzollini said. "I will not take that away from her."

But she soon found out that her son's surgery wasn't covered by her insurance, Health Net. When they didn't pay, the doctor's office started coming after Azzollini instead of negotiating with the insurance company, telling her she owed money for "services rendered" or it would show up on her credit report.

"The problem needed to be worked out between the insurance company and the doctor," Linda Leu, who works at a California patient advocacy group called Health Access, told KGO. "And the provider should not have immediately turned to the consumer to try to bill them."

Still, Leu said the practice is not uncommon because doctors and insurance companies tend to disagree about compensation.

Azzollini said she called Health Net, but they "barely" talked to her, and her insurance agent wasn't able to help either. Defeated, she started to pay the doctor the thousands of dollars she owed, until a friend told her to contact the consumer protection team at KGO-TV, the ABC News affiliate in San Francisco.

KGO reporter Michael Finney took the challenge, bringing 20 years of experience "fighting for the little guy" with him. He said companies know that he's not going to give up easily.

"She may have resolved the issue, but as a lone consumer, it is hard to be heard and taken seriously," Finney told ABCNews.com.

Once Finney got involved, the insurance company discovered that Lucas' hospital visit had been incorrectly coded "outpatient" instead of "emergency," altering the coverage.

"Health Net strives for excellent service at all times, and we are glad for the opportunity to remedy the situation on behalf of our member," the company said in a statement.

The issue took about two weeks to resolve in November, with the insurance company paying the doctor on Nov. 29. On Jan. 15, the doctor's office reimbursed Azzollini for full amount she'd paid so far: $2,655.40.

"We want consumers to know that when billing errors occur, there is a way - no matter what they have been told - to get things righted," Finney said.

Consumers should communicate with providers when they visit the emergency room to see whether doctors are within their network, said Cheryl Fish-Parcham, the deputy director of health policy at Families USA, a national consumer-protection nonprofit. She said the hospital can specifically assign doctors who are covered.

Fish-Parcham said many states have laws designed to help the consumer in an emergency.

"A few states have laws that require an out-of-network provider and the insurance company to negotiate payment in emergency situations and hold the consumer harmless for everything except co-pays or co-insurance," she said. "There also might be laws in your state requiring some disclosure that providers who treat you in a hospital might be out of network."

She said consumers can also appeal if they think they've been billed inappropriately.

To find out about health insurance assistance programs in your state, click here.