Tampa, Florida (CNN) -- Dianne McLeod recalls her husband, Stanley, getting so visibly upset when the debt collectors called that she had to take the phone away from him. She believes constant harassing phone calls and other tactics eventually killed him.

"I think they were a major contributor to his death because of the stress and what I saw it doing to him," she said.

McLeod is suing her mortgage company, Green Tree Servicing, for the wrongful death of her husband. McLeod said she thinks he would be alive if not for the stress caused by Green Tree's debt collectors. She said they sometimes called up to 10 times a day and also called the McLeods' neighbors.

"He would begin to sweat; he would also get very red in the face and complain about chest pains," McLeod said. "We were worried he was gonna have a heart attack right there on the phone."

Stanley McLeod had a heart condition and in 2002 was airlifted to a hospital after a second heart attack. He went on disability and Dianne McLeod says they fell behind about three months on their mortgage payments.

This is a message left on the their home answering machine, allegedly by a male Green Tree representative:

"Stanley McLeod, you need to call Green Tree and get your act together and make your payments on your mortgage and quit playing these games.

"Why don't you have that helicopter pick you up and bring that payment to the office?"

It's a phone call the McLeod family will never forget.

"It was so inhumane to talk to someone like that and to take an event that was traumatizing to him and to make a jest out of it," McLeod said.

Stanley McLeod died of heart failure in 2005.

"The collection activity did not lead to his death. The claim is meritless," said Senior Vice President and General Counsel Brian Corey of Green Tree Servicing.

"We deny that the content, the number or the timing of the calls had anything to do with him dying in 2005," Corey said.

Debt collection is regulated by the U.S. Federal Trade Commission, which forbids harassing consumers. Companies can be fined $16,000 per incident. This year, as the economy plunged, consumer complaints shot up. More than 45,000 complaints had been received by the FTC through the end of June, up about 20 percent over last year.

The Association of Credit and Collection Professionals represents about 5,500 companies in the industry.

"The vast majority are very ethical, caring individuals who look for resolution to problems," said Adam Peterman, the organization's director of federal government affairs.

"A bad apple can spoil the bunch too often, so we have to keep pushing that rock up the hill to help prevent that," he said.

Billy Howard is an attorney who runs the Consumer Protection Division for Morgan & Morgan. Howard represents McLeod and has about 500 similar cases against companies who use what he called "Tony Soprano tactics," a reference to the fictional organized crime leader who was the central character in the HBO drama "The Sopranos."

"I think it's frightening because these companies go after people and they utilize tactics people just don't know are illegal," Howard said.

"Scare tactics work. They've worked for years. That's how the mafia made so much money. That's how these mafia-like tactics result in so much money. People are scared," he said.

Howard says one of his other clients had this message waiting on the answering machine:

"You're a piece of s---. That's why you turned your phone off. Mother f-----. But that's OK.

"You haven't heard the last of me. But if it takes me a year or takes me two, believe me, I will find you. You better move. But if you move, you better move to California, 'cause I do travel. And I like traveling. Goodbye."

And then there was this one:

"When I see you. I'm gonna f--- you up. I want my money, and I want it now. I hate people who lie to me and abuse my company. ... If you bring my money back, you don't have to worry about me, just disregard my message."

The FTC said it receives more complaints about debt collectors than any other industry. Complaints are also filed directly with attorneys general in all 50 states, which can open state investigations. Of the 45,000 complaints received by the FTC in 2009, the agency opened one investigation.

According to FTC officials, their primary role is to be a backstop to lawsuits brought by consumers, which is the primary way to fight the alleged abuse.

"We don't have the manpower to individually investigate all of the complaints," said Tom Pahl of the FTC's division of financial practices.

"We try to target the worst actors," he said.

The FTC urges consumers with complaints to report them to their state attorney general, to the FTC and to consider filing suit against the company they believe is harassing them.

Anna Inglett is president and CEO of PHG Financial Recovery Services in Tampa, Florida.

"Those companies that do that will eventually put their own selves out of business. ... We want them gone. We want them all gone," she said.

But she also said debt collection is an important part of the economy.

"If we did not have debt collectors that helped businesses get the money that's owed to them, then who voluntarily would pay any bills?" she said.

McLeod said she remembers the endless phone calls at all hours of the day and night.

"They did not seem to care. ...They didn't care what they said or how many times they called," she said.

The trial is scheduled to begin in January.