Discover Financial Services, one of the nation’s largest credit-card issuers, will refund $200 million to 3.5 million customers it led into buying costly and unneeded credit-card products, federal regulators announced Monday.

In some cases, customers were enrolled in the payment-protection plans and other products without their consent. Discover provided scripts to call-center agents that suggested customers would not be charged until they had reviewed written materials. Yet those materials were not provided until after the firm took money from consumers.

Telemarketers used scripts that “failed to disclose material terms and conditions” of protection products and “spoke more rapidly during the mandatory disclosure portion of the sales call,” regulators said in the enforcement order against Discover.

The credit-card firm also will pay a civil fine of $7 million each to the Consumer Financial Protection Bureau and the Federal Deposit Insurance Corp., which issued the joint enforcement action.

“People deserve to be treated fairly by their financial institutions,” CFPB director Richard Cordray said during a call with reporters. “We will continue to work toward that goal with great determination.”

The charges against Discover mirror those the CFPB leveled at Capital One Bank, which had to pay $210 million in July for selling unnecessary credit-card services to the unemployed or people with poor credit. Cordray told reporters on Monday to expect additional actions against financial firms engaged in deceptive practices.

Discover settled the charges without admitting or denying any wrongdoing, but it agreed to submit to an independent audit and stop the practices in question.

“We have worked hard to earn the loyalty of our cardmembers, and we are committed to marketing our products responsibly,” David Nelms, chairman and chief executive of Discover, said in a statement.

Discover will refund consumers who purchased at least one of its add-on services between December 2007 and August 2011. The average payout is expected to be about $56 per cardholder.

Consumers will be reimbursed at least 90 days’ worth of fees paid for the products, unless they made use of the payment-protection plan. About 2 million Discover customers will receive full reimbursement of all the fees they paid.

Eligible consumers who still have a Discover account will receive a direct credit, while others will receive a check in the mail before 2013.

Discover has been battling accusations it misled customers about its payment-protection product since 2010, when the first of eight separate class-action lawsuits was filed against the firm.

A U.S. District Court judge in Illinois in May approved an $11 million global settlement addressing all of the class-action cases. But Discover is still contending with similar lawsuits filed by state attorneys general in West Virginia and Hawaii.

Consumer advocates and government agencies began questioning the usefulness of payment-protection products as lenders began aggressively marketing them during the recession. Payment-protection plans can cover a cardholder’s debt if he or she dies or faces an unavoidable financial crisis.

Researchers at the Government Accountability Office found that consumers paid $2.4 billion in fees for payment-protection products in 2009. They looked at nine credit card issuers, including Capital One and Discover, and determined that consumers received little “tangible financial benefit” from debt-protection services.

Lenders have started backing away from these products as regulators intensify scrutiny of their sales tactics. Citigroup in August halted telephone sales of payment-protection services as it reviewed its sales practices, while Bank of America stopped offering credit-protection products to new consumers.