WASHINGTON — Shawn Traylor of Stamford, Conn., still doesn't know what the debt was for or how much it was.

He did know it wasn't his, and he knew he wasn't going to pay it.

So when bill collectors started calling four to five times a day in March, Traylor, a 39-year-old finance officer, sent them a letter asking them to verify that the unknown debt was his.

When he got no reply, he sent another letter, this time by certified mail, asking that they stop calling his home since they never verified that he was the delinquent account holder.

Instead, Traylor said, the collection agency called the next day. "And the day after that, and the day after that and the day after that," he recalled.

Sergei Lemberg, Traylor's attorney, said the continued calls after Traylor asked in writing that they stop were a violation of the Fair Debt Collection Practices Act. The law bars debt collectors from using abusive, unfair and deceptive tactics to force consumers to pay.

Since the recession hit in 2007, federal lawsuits filed under the Fair Debt Collection Practices Act have more than doubled, while complaints about problem collectors have skyrocketed.

In addition to Traylor's lawsuit, which is in settlement negotiations, Lemberg's firm has filed about 1,500 such lawsuits in the past three years. He said the economic downturn has created a nightmare for cash-strapped borrowers and lenders now saddled with delinquent accounts.

"I think debt collectors have become more aggressive by necessity because folks just have less money. And how do you collect more from people who have less money? You have to become more aggressive," Lemberg reasoned.

As a result, consumers feel cornered. "And consumers are more likely to think legal when they're being cornered," Lemberg said.

The numbers suggest he's right. In 2007, nearly 4,400 federal lawsuits were filed for alleged violations of the law, according to WebRecon, a website that tracks the filings for the collections industry.

As the recession deepened, the number rose to 6,000 in 2008 and then to nearly 9,300 in 2009. This year, filings are on pace to reach nearly 12,000, said Jack Gordon, the president of WebRecon.

Unlike Lemberg, Gordon doesn't think the filing frenzy is rooted in the recession. He said the spike in lawsuits began years before the economy tanked. The greater culprit, he asserts, is the Internet.

"You can't type the name of a collection agency into a search engine without getting bombarded by (advertisements) from consumer attorneys begging you to call them before you pay a penny to a collection agency," said Gordon, a former debt collector who left the business over frustration with frivolous lawsuits.

Generally, debt collectors can't contact you at inconvenient places or times, such as at work or between 9 p.m. and 8 a.m. — unless you okay it. The law also prohibits bill collectors from threatening violence, using profane language, or using the phone to annoy someone. Collectors also can't lie or misrepresent themselves or the amount a consumer owes.

The law requires that collectors, within five days of first contacting a consumer, send a written "validation notice" that gives the name of the creditor, the amount owed and what to do if you dispute the debt.