Timesaver Inc., a Rockville firm that promises to get credit cards for people who've had trouble qualifying for credit, agreed yesterday to return thousands of checks sent in response to advertisements that postal inspectors charge are misleading.

Timesaver agreed to refund customers' money after U.S. Postal inspectors sued the firm in U.S. District Court in Baltimore for allegedly violating postal regulations.

Timesaver falsely advertised that credit card approval was "automatic" when it was not and failed to tell customers they had to open a $300 savings account with an affiliated savings and loan association before they could qualify for a credit card, the inspectors charged.

Under the arrangement with United Savings and Loan of Vienna, Timesaver customers in effect deposited their own money in a savings account at 5 percent interest, then borrowed the money back at the credit-card rate of 18 percent or more.

Even some customers who put up the $300 were turned down for the MasterCard and Visa account they wanted, and several consumers were not given their money back as promised, the postal inspectors alleged.

Accusing Timesaver of "conducting a scheme or device for obtaining money or property through the mails by means of false representations," the postal inspectors took the unusual step of seeking a court order to hold up the firm's mail.

Instead of granting the order, U.S. District Court Judge Alexander Harvey II told Timesaver to negotiate a settlement with the Post Office.

No agreement was reached during a morning meeting, but late yesterday Timesaver founder David Meyers said he had consented to a "completely voluntary" refund plan. Meyers said Timesaver would return all checks it receives in response to the ads the postal inspectors complained about and will revise its brochures and letters for future solicitations. He said he could not estimate how many $25 checks would be returned.

Meyers, chairman of the Rockville firm, called the charges "absolutely untrue" and claimed his company is the victim of "the biggest railroad job you ever saw." He charged that department stores, banks and other credit-card issuers are trying to put his unique service out of business.

Meyers launched Timesaver in 1974 when he was playing oboe with local orchestras. He claims the Rockville firm is the biggest credit-card marketing company in the world.

The federal civil suit against Timesaver was filed after investigations of the company by the Federal Trade Commission, the Montgomery County Consumer Affairs Office, the Maryland attorney general's office and postal inspectors.

The Maryland attorney general's consumer unit has received more than 50 complaints about Timesaver and is investigating the firm's operations, a spokesman said.

The state attorney general is planning to file civil charges similar to those raised by the postal inspectors against Timesaver, sources familiar with the investigation reported. Other agencies said they have referred the matter to the state agency and to postal inspectors.

Timesaver advertises heavily on television in the Washington area and distributes millions of "take-along" brochures through displays in stores, hotels, restaurants and other businesses.

"Take a card. Any card," Timesaver urges consumers in a brochure illustrated with a hand holding a royal flush of plastic money.

When it first went into business during the heyday of consumer credit, Timesaver offered individuals the chance to apply for as many as a dozen different credit cards by filling out one application.

Last spring, the firm began offering a new service in which it promised to get a MasterCard or Visa for people who "for any reason were unable to secure the cards."

In a direct mail advertisement cited by postal inspectors, the company promised "Timesaver applicants are automatically approved for MasterCard and Visa." There is a "one-time fee" of $25, the solicitation said. "If for any reason Timesaver cannot approve your application, your $25 processing fee is immediately refunded," the company promised.

Persons who sent in applications got them back stamped "approved" but that didn't mean they had been approved for a credit card, postal inspectors complained.

The approval came only from Timesaver -- which has no power to give a credit card to anyone -- explained inspector Tom McLure. Timesaver customers still had to have their credit okayed by the lender. If they were turned down, Timesaver refused to refund their $25 on the grounds that it had "approved" the credit application.

Consumers were also misled because they were not told they would have to open a savings account at United Savings and Loan to qualify for a credit card, the postal inspectors said. United also charged customers a $25 fee for the MasterCard or Visa, a fee not mentioned in Timesaver's ads.

The customer had to deposit at least $300 in the savings account in order to qualify for a $300 line of credit. A bigger deposit entitled the customer to a bigger credit line or a second credit card.

There's nothing illegal about such a scheme, so long as it is disclosed to the customer, postal officials noted.