It's bad enough that record numbers of people are losing homes because of mortgages they couldn't afford and should never have gotten. Mortgage companies shouldn't add insult to injury by overcharging borrowers already in foreclosure. Fortunately, a federal monitor is moving to stop such abusive practices. The threat of congressional action should also motivate the industry to improve its behavior.

At the center of the federal investigation is Countrywide Financial Corp., the nation's largest mortgage lender and loan servicer. The U.S. Trustee for the bankruptcy courts has subpoenaed Countrywide seeking documents related to suspect fees in at least a dozen cases nationwide. Two of the cases involve Miami and Boca Raton couples who, like many homeowners trying to salvage their homes, filed for Chapter 13 bankruptcy.

In the Miami case, the trustee is questioning an $11,924 escrow advance and an insufficient funds fee of $683 that Countrywide charged the borrower. The trustee also wants to know why the mortgage company more than doubled the monthly mortgage payment.

Countrywide has argued in court filings that the U.S. Trustee, a division of the Justice Department, is overstepping its authority. The trustee rightly responded that it has a legal obligation to protect the public. Mortgage companies that misrepresent claims, moreover, threaten the integrity of the bankruptcy courts.

The issue is disturbing considering how frequently lenders add suspect and unsubstantiated charges to troubled mortgages. A recent study by a University of Iowa law professor found questionable fees in almost half of the 1,700 foreclosure cases examined. In one extreme example, a lender claimed a borrower owed more than $1 million when loan documents showed only $60,000 of mortgage debt left. Questionable charges for property inspections, appraisals and late payments are not unusual.

Bankruptcy judges also are taking note. Recently, judges in Ohio threw out 73 foreclosure cases after the mortgage firms failed to provide proof of their claim to the properties in question. Yet other borrowers in bankruptcy, overwhelmed by debt and financially unsophisticated, may not know to contest the lender.

Washington, too, is finally acting. An administration-brokered industry plan could offer relief to some borrowers by freezing low, introductory interest rates that would otherwise jump to unaffordable levels. Congress is weighing a number of measures to tighten mortgage laws. One bill would help borrowers keep their homes by allowing bankruptcy judges to change mortgage-payment terms. Such a bill could gain traction unless the industry takes steps to stop overcharges and other mortgage servicing abuses.