Wells Fargo CEO Tim Sloan apologized Tuesday for the bank's fake accounts scandal but was peppered with criticism by U.S. senators who expressed skepticism about whether the bank has truly changed.

Sloan jostled on several occasions with Senate Banking Committee members, including Sen. Elizabeth Warren, D-Massachusetts, who called for him to be fired.

"I’m not afraid to make hard decisions when it’s needed," Sloan said in a testy exchange with Warren, defending his record as an agent of change at the company.

"You really want to say, are you kidding?" Warren said.

Wells Fargo CEO Timothy Sloan arrives to testify before the Senate Banking, Housing and Urban Affairs Committee hearing in Washington, D.C.

Sloan, the company's former chief financial officer, assumed the top job after former CEO John Stumpf exited following the scandal. Sloan has taken steps to further investigate the matter and pledged to compensate victims.

But Warren accused Sloan of repeatedly promoting the bank's ability to open new accounts in the years before the scandal was exposed.

"You made money personally off of it," she said. "At best you were incompetent. At worst you were complicit."

Sloan, clearly annoyed, challenged Warren's reporting of his past remarks. "You're wrong," he said.

In another chippy exchange, Sloan refused to give up Wells Fargo's right to force customers into arbitration to resolve future disputes.

Sloan said the company is refunding "every nickel" of unauthorized fees and excessive borrowing costs that customers incurred because of the scandal. He said the company would not force any victims of the scandal into arbitration.

But Sen. Sherrod Brown, D-Ohio, asked whether Wells would relinquish its right to force all customers into arbitration.

"No I won’t, Senator," he said.

"C'mon!" someone in the audience exclaimed.

Wells Fargo disclosed in August that it had discovered as many as 3.5 million potentially authorized accounts dating back to 2009, up from a previous estimate of up to 2.1 million.

Since then, the bank's use of the private arbitration process to force customers to resolve disputes outside of the traditional courts process has come under scrutiny.

"I am deeply sorry for letting down our customers and our team members," Sloan said Tuesday. "I apologize for the damage done to all the people who work and bank at this important American institution."

In all, consumer and small business owners of approximately 190,000 accounts incurred Wells Fargo fees and charges, up from roughly 130,000 accounts previously identified. The bank said it would provide a total of $2.8 million in new refunds and credits beyond the $3.3 million previously refunded.

The expanded review also examined online bill payment services and found approximately 528,000 potentially unauthorized enrollments. Wells Fargo said it would refund $910,000 to customers who incurred fees or charges in connection with the services.

"If there is a problem, we want to hear about it," Sloan said Tuesday. "You expect us to do better, and so do we."

The scandal came to national attention in September 2016 when the bank was hit with $185 million in penalties by the Consumer Financial Protection Bureau, the Office of the Comptroller of the Currency and Los Angeles legal officials for secretly opening unauthorized deposit and credit-card accounts that harmed customers.

An investigation conducted by the authorities found Wells Fargo employees improperly boosted the bank's sales figures by covertly opening the accounts and funding them by transferring money from customers' authorized accounts without the owners' knowledge or permission.

The bank has since ended incentives for branch employees who open new accounts.

The bank has also clawed back more than $180 million in executive compensation.

Beyond the refunds prompted by the new review, the bank said it has provided more than $3.7 million in refunds and credits to customers for complaints and mediation claims from Sept. 8, 2016, through July 31, 2017.

Bank customers whose credit scores were affected by the accounts scandal also may receive compensation under a recent $142 million class-action lawsuit settlement for claims that date back to 2002.

The bank also disclosed in July that it would make $80 million in payments to more than 570,000 auto loan customers who also were charged for auto insurance without their knowledge.

Contributing: Kevin McCoy

Follow USA TODAY reporter Nathan Bomey on Twitter @NathanBomey.