If harassing calls from debt collectors are keeping you from answering the phone — or stressing you out — you’re not alone.

Amid the tough economy, debt collection activity has intensified, with some debt collectors engaging in unfair, abusive or illegal practices. The Federal Trade Commission says it gets more complaints about debt collectors than any other industry. In 2009, the agency received 88,190 consumer complaints about debt collectors, up 12% from the year before.

Under the Fair Debt Collection Practices Act (FDCPA), you have the right to sue if overzealous bill collectors break the law. Violators could be liable to you for statutory damages of up to $1,000, plus actual damages suffered and your attorney’s fees.

Before you rush out to hire a lawyer, though, you’ll still have to deal with those pesky calls. So here are three things you should never say to a debt collector:

1. “I can send you a post-dated check.”

The FDCPA prohibits debt collectors from misusing postdated checks. But that doesn’t mean that unscrupulous debt collection agencies don’t routinely break the law. In fact, experts say it’s not uncommon for bill collectors to deposit a postdated check prior to its date.

“You can set yourself up for another nightmare if you give a debt collector a post-dated check and they run off and cash it early,” says Rodney Anderson, the author of Credit 911: Secrets and Strategies to Saving Your Financial Life.

“If they do cash it before the date, your account might not have enough money to cover everything and you could also be stuck with bounced check fees,” adds Anderson, who is also the executive director of Supreme Lending, a Plano, Tex.-based mortgage banking firm.

2. “My bank or bank account number is … “

It’s not a debt collector’s right to know where you bank or to obtain your bank account number — even if you do have a past-due debt.

Nevertheless, some overwhelmed consumers who want to be debt free, or who just want to get debt collectors off their backs will give up way too much information, like their bank account number and other financial data. Not only is this sensitive personal information none of their business, but divulging this information can backfire on you.

“Let’s face it: Not all collection agencies are run the same way. Some are crooks,” says Anderson. “So you’ve got to be very careful about whom you’re giving your credit card, debit or checking account information.”

Even if you agree to pay a lump sum or to make monthly payments on a debt, don’t do it via automatic withdrawals from your checking or savings account. Instead, pay with a money order or a cashier’s check from a bank other than your own bank. Then hold onto your documentation as proof of payment.

What if you’ve already made the mistake of supplying a debt collector with your financial account information? Monitor your account very closely for the next few months. If some rogue collector does tap into your bank funds, be prepared to immediately dispute the withdrawal with your financial institution.

3. “I’m trying to clean up my credit for a loan.”

Assume for a moment that the debt collector hasn’t tracked you down. Instead, it’s the other way around. You’ve reached out to them. Most likely it’s because you want to clear up something in your credit files for one reason or another.

People often try to do away with old debts when they’re in the market for a loan, like a mortgage or auto financing. But that doesn’t mean you should tell that to a debt collector.

“You’ve got to be strategic when you’re dealing with collection agencies,” Anderson says. If you spill the beans that you need to spruce up your credit for a loan “you’ve taken all your negotiating power and thrown it out the window.”

Keeping this information private means the debt collector won’t be able to use it as leverage against you.

In all circumstances, request that a debt collector validate an alleged debt. This means they should notify you, in writing, which company they’re collecting for and spell out exactly what you owe.

If you agree to pay an outstanding debt, negotiate to get the debt collector to delete the negative information from your credit reports at Equifax, Experian and TransUnion. And get such an agreement in writing before making a payment.

Free Debt Help and Advice

If you or anyone you know is struggling with debt, read my New York Times best-selling book, Zero Debt: The Ultimate Guide to Financial Freedom.

Also, realize that it’s illegal for debt collectors to call you repeatedly, phone you before 8 a.m. or after 9 p.m., or contact you on the job if you say you can’t receive calls there. To stop this kind of harassment, write a “cease contact” or a “cease and desist” letter to the debt collector. If the harassing calls don’t stop, report the company to the FTC and the Better Business Bureau.

Lastly, for those dealing with multiple debt collectors, it may be wise to pick and choose your battles. Anderson says far too many consumers let small bills of perhaps just $30 to $100 mar their credit rating for years, keeping them from getting approved for loans or obtaining better credit terms.

Sometimes, he adds, consumers need to go ahead and pay smaller, nuisance bills when they know they really do owe the money.

“I tell people to pick up the phone and talk to these collection agencies because there really are solutions to the problem,” Anderson says, “and avoidance alone won’t help.”