WASHINGTON — The chief executive of Chase Card Services, one of the nation's five largest credit-card issuers, will apologize to Congress today for charging a financially strapped customer $7,500 in interest charges and late fees on purchases of $3,200, the company said yesterday.

Richard Srednicki's apology before the Senate permanent subcommittee on investigations will follow testimony by the customer, Ohio resident Wesley Wannemacher, on how Chase's penalty fees and interest charges made his initial bill triple over six years.

The hearing by the subcommittee, part of the Homeland Security and Governmental Affairs Committee, will examine practices in the credit-card industry that subcommittee Chairman Carl Levin, D-Mich., says are "unfair" and "unethical."

The hearing follows a Senate Banking Committee hearing in January on credit-card industry practices. The two are part of a wider focus by the new Congress, now controlled by Democrats, on financial practices that affect rank-and-file consumers, including practices in the home-lending and retirement-savings industries.

Wannemacher has paid the bank $6,300 — nearly twice the amount of his original bill — since March 2001, but at the end of February still owed $4,400.

Last week, after subcommittee staff called Chase for comment on the situation, Chase officials telephoned Wannemacher to say that he no longer owed the bank the $4,400 and that the bank erred in imposing so many penalties. Bank officials yesterday said they should have put him in a repayment assistance program in 2005, where many penalty fees and charges would have been waived. Chase said that as a result of his case, it will no longer charge additional over-limit fees after a customer is over his or her limit for more than 90 days.

"Clearly, some companies have stepped over the line," the subcommittee's ranking Republican, Sen. Norm Coleman of Minnesota, said at a briefing yesterday about what subcommittee staffers found after a months-long investigation of credit-card industry practices.

Last week, Citigroup, which also will testify today, announced that it would end two policies that consumer groups and some members of Congress have criticized as unfair and abusive — "universal default," under which a cardholder's interest rate on a Citibank card increases if the holder is late on a payment for another, non-Citibank credit card; and reserving the right to raise a customer's credit-card interest rate at "any time for any reason."

Senate Banking Committee Chairman Christopher Dodd, D-Conn., and Levin have told the industry that it must fix such problems or expect lawmakers to take action, either by pushing bank regulators to tighten lending rules or by introducing legislation banning the practices.