Ask ahead of time for lien waivers from subcontractors and suppliers, who can otherwise tap you for payment if the contractor reneges on compensating them.

Remedies. Local chapters of the National Association of the Remodeling Industry (800-611-6274) mediate disputes involving their members. "If the panel finds that a homeowner has a legitimate complaint, the contractor is expected to make good," says Gwen Biasi, of NARI. You can also seek help from consumer-protection bureaus, licensing agencies and the state attorney general's office.

If you live in a state that licenses contractors, you may have access to a guaranty fund that compensates you for losses caused by poor workmanship or failure to complete a job. In Massachusetts, for instance, you can recover up to $10,000 through the state fund. Ask the local licensing board how to pursue a claim.

Cell-phone runaround

Your wireless-phone bill includes an overcharge, and you can't make the company set things straight. Now your service is in jeopardy.

Rights. The Federal Communications Commission, along with about one-third of the states, regulates cell-phone practices, including billing problems and "cramming," or charging you for services without authorization. But jurisdiction is murky, says Patrick Pearlman, of the West Virginia utilities commission, so you should expect to fight for redress in this lightly regulated field. Says Pearlman, "Wireless service has mostly been left to the Wild West of deregulation and nonenforcement."

In a recent two-month period, for instance, ConsumerAffairs.com received more than 100 complaints about Cingular's billing and network problems following a merger, as well as the pass-the-buck attitude of its customer representatives. Typical consumer comment: "I don't have the time or money to be dealing with these people!"

Remedies. First, call your carrier. Often what appears to be an error is a misunderstanding of the plan, says Tom Pica, of Verizon Wireless, which leads the industry in customer-satisfaction surveys. "We'll work with customers to adjust the plan or get them on the right plan. Our customer-service reps have the authority to do that."

Failing a fix, call an advocate. "We have set up special contacts with phone companies to get problems resolved," says Shirley Rooker, of the Call for Action Network.

Although many states defer to the FCC on cell-phone issues, you might get results by contacting your state attorney general's office or utility commission. Says Pearlman, "I'd call my utility commission and raise blue hell" -- for example, by asking the commission to demand that the carrier either justify the charge or remove it.

Finally, contact the FCC, which mediates complaints and occasionally takes enforcement action (use Form 475, available at www.fcc.gov, or call 888-225-5322). If the problem involves state jurisdiction, the FCC will forward your complaint to the appropriate agency.

Airline hassles

You were bumped from your flight without compensation and spent the night on a chair at the airport.

Rights. Federal regulations entitle you to the cost of the fare to your destination, up to $200 in cash, if you're bumped from an overbooked flight against your will and the substitute flight arrives one to two hours after the scheduled time. If you are delayed by more than two hours, you get double the compensation, up to $400 in cash. Conversely, if you arrived at the gate after check-in time, or if the flight was switched to a smaller plane or canceled altogether, you're not owed any payment, although most airlines will book you on the next flight on which space is available. Each carrier sets its own policy for rewarding volunteer bumpees. Expect a seat on a later flight and some compensation, such as a voucher for future flights.

Remedies. Beyond the company's written policy, gate agents have discretion to bestow dollar-amount vouchers for future flights, as well as for airport meals or an overnight hotel stay while you wait for the next plane out. If you think you deserve more than you're being offered, ask to see the airline's customer-service representative at the airport.

Sometimes getting on the flight is worse than being stranded. To complain about brusque flight attendants or butterfingered bag handlers, write to the airline's CEO or customer-service manager (whose address is listed on the Web site of the Aviation Consumer Protection Division of the Department of Transportation).

If you're still steaming, tattle to the DOT's consumer division, which publishes a tally of complaints about each airline in its monthly Air Travel Consumer Report.

Faulty credit report

Your credit report wrongly states that you reneged on a debt, causing your credit score to plummet.

Rights. Under the federal Fair Credit Reporting Act, credit bureaus must review disputed information and change entries that are wrong or incomplete, or that can't be verified. You're entitled to a response within 30 to 45 days.

Remedies. Fill out the form that comes with your credit report and gather copies of any paperwork -- for instance, a credit-card statement or a canceled check -- that support your position. Mail everything to the credit bureau and send copies to the creditor.

If you've been a victim of identity theft, file a police report. Then send a copy to each of the three major credit bureaus, along with a request that they block the offending information and put a fraud alert on your account. For more information on handling identity theft, visit www.privacyrights.org.

If the creditor refuses to back you up or the credit bureau fails to correct your record, contact your state attorney general's office, which has authority to enforce the federal law and deal with complaints informally. (The Federal Trade Commission investigates patterns of abuse but not individual cases; call 877-382-4357.)

As a last resort, hire a lawyer, recommends Eric Bourassa, of MassPIRG, a consumer-advocacy group. Federal law notwithstanding, credit bureaus are notorious for dragging their feet, says Bourassa. "A lawsuit should get their attention."

Internet-auction fraud

You won an auction on eBay, but the item never arrived.

Rights. Companies that do business by mail must fulfill orders within 30 days of the order (or the end of the auction) unless another delivery time has been arranged. If you paid with a major credit card, you can contact your card issuer and dispute the charge. Otherwise, you're covered by eBay's Standard Purchase Protection Program, which reimburses losses up to $175. PayPal, the online-payment service, provides coverage up to $1,000, but only on items that carry the PayPal-protection icon.

Remedies. Go to www.ebay.com/securitycenter and click on the "Item Not Received" link. Then use the so-called dispute console to discuss the problem with the seller, a prerequisite for filing a complaint. The seller has ten days to respond, after which you can file the claim with eBay. (Claims that qualify for PayPal reimbursement are forwarded to PayPal's Web site.)

You have only 45 to 60 days after the auction closes to initiate a claim, and fraudulent sellers have been known to promise delivery until the clock runs out. In that case, file a complaint with the Internet Crime Complaint Center (www.ic3.gov), which refers complaints to the appropriate law-enforcement agencies. In 2004, the center referred 190,000 complaints, of which 71% involved Internet-auction fraud. The U.S. Postal Service also refers complaints; go to www.usps.com/postalinspectors/fraud/contactus.htm.