In June Rosemary McDougall got an unsolicited phone call at dinnertime from a telemarketer selling automotive warranties.

"I find it more than coincidental," says her son, Graham, "that she had taken her car to the dealer for repairs the day before. But they deny providing her car or contact information to the caller."

The phone solicitor had specific details about her 2002 Dodge Durango—no longer under factory warranty but driven only 21,000 miles—and persuaded her to buy a "protection" policy for $295.

"It sounded like a good deal," says the 82-year-old widow, a cancer survivor who lives in Metairie, La. She gave her credit card number to the salesman—but immediately regretted it.

The next day, McDougall, a retired IRS auditor, called Colby Evans, the salesman from Automotive Warranty Solutions. The Florida-based company has generated numerous complaints, often for telemarketing to people who, like McDougall, are enrolled in the National Do Not Call Registry.

"I left several messages, but he never returned them," Rosemary McDougall says. Her son, a gerontologist at the University of Texas School of Nursing, Austin, intervened and eventually reached Evans. "He told me, 'Your mother bought it, and we're not going to cancel.' Then he hung up on me."

Two weeks later a bill arrived in the mail from Automotive Warranty Solutions. "It was for $2,700, the 'balance due' on that $295 policy, which already had been charged on my mother's credit card," says Graham McDougall Jr. "I have no doubt they were trying to scam her. She was vulnerable and exhausted from her chemotherapy."

Only after Graham complained to the Better Business Bureau, the Federal Trade Commission and AARP did his mother get her $295 refunded and the policy canceled. Automotive Warranty Solutions CEO Ralph Mancuso also wrote a letter of apology to McDougall, but he declined to comment to Scam Alert.

Since taking effect in 2003, the Do Not Call Registry has significantly curtailed the number of unwanted phone sales calls. Still, the FTC, which manages the list, gets 3 million complaints a year from registrants. Here's how to prevent unwanted sales calls—and protect yourself if you make a telemarketing purchase you later regret:

• Re-register. Those enrolled in the Do Not Call Registry must re-register after five years. To verify when you need to re-register—or sign up for the first time—visit www.donotcall.gov or call 1-888-382-1222 toll-free.
• Act locally. Some states operate their own do-not-call registries. Go to www.ataconnect.org for a list of state programs.
• Check caller ID. Telemarketers are required to display their phone numbers and, if available, the name of the company selling the products. Be wary of ID numbers marked "private" or "unknown"—and never buy from a caller who won't give a callback number.
• Sleep on it. No matter how enticing the offer, don't buy during the sales call. Don't reveal your credit card number without getting a written contract with all the terms, and don't trust anyone who asks for a fee upfront.
• Know the rules. Some states allow up to three days to cancel a purchase from a telemarketer; in others the sale isn't final until you receive written confirmation from the seller—and there may be a brief grace period after that.
• Complain. You can file a complaint about unsolicited calls with your state consumer office or with the FTC (go to www.donotcall.gov and click on "File a Complaint") if you've been on its registry for at least 31 days.

To learn more, go to the National Fraud Information Center at www.fraud.org and click on "Telemarketing Fraud."

Sid Kirchheimer is the author of AARP/Sterling's Scam-Proof Your Life.