Susan Monnig can now swing a golf club like a pro.

"I can do everything I want," Monnig said. "I can do things I haven't been able to do since I was 12 years old."

Although she feels great physically, Monnig says her insurance company is dragging her down mentally.

The company is refusing to pay for the knee replacement surgery that got her back on her feet, although Monnig says other insurance companies cover the procedure.

Monnig said the operation was approved and she waited six months for the surgery. Two weeks before the operation, her insurance company pulled the plug.

"To get out of paying it, they say it's investigational," her husband, Joe Monnig, said.

The Monnigs are stuck with an almost $50,000 hospital bill and are running out of options.

"You look at the insurance community and you just have to wonder, 'what in the hell is going on with these people?'" Joe Monnig said.

5 Investigates wanted to know what the insurance companies were thinking as well, so reporter Morgan Loew talked to experts and learned that health, home and auto insurance companies are under increasing pressure to cut costs and increase profits. This means filing a simple claim can turn into an extended nightmare for the consumer.

Hurricane Katrina first exposed the insurance companies.

Thousands of homeowners were forced to go to court to get their claims paid. The result is that the public now knows how far some of the nation's largest insurance companies will go to avoid paying claims.

That strategy also applies to health and auto insurance.

For example, if an insurance company saves $1,000 on one car accident by reducing what it pays the policy holder, and then repeats that process 100,000 times in a year, the company saves a staggering $100 million.

Experts say it's happening.

"When they turn the claim-handling center into a profit center, which is what a lot of them have deliberately done, that in and of itself is bad faith," said Scottsdale attorney Stephen Ryan.

Ryan says an increasing number of consumers are fighting back when their claims are denied by going to court.

That's what the Monnigs may have to do, because they're at an impasse.

5 Investigates researched the procedure their insurance company calls "investigational," and found that it is fully FDA approved.

It's also covered by several insurance companies, including Monnig's, operating in other states.

"I'm not going to just let this go away," Joe Monnig said. "It's not just for us. It's for other people."

The insurance industry says it has increased profits by working smarter, not by cheating people on their claims.

A system is in place to appeal claims for people who feel they've been treated unfairly.

Experts offer advice for people whose claims are denied. They say you should never accept the first offer if you don't think it's fair.

Always appeal the first denial of payment.

When you file an appeal, make your case by proving that your claim is reasonable. Use classifieds to show that your car is worth more. Get a doctor to say your procedure is necessary. Stick it out for as long as you can.

Insurance companies are required to show customers how to file appeals.

Click here for more instructions.