(Reuters) - Wells Fargo & Co WFC.N said on Tuesday an internal underwriting error had caused it to reject home loan modifications, resulting in the bank foreclosing more homes than expected.

FILE PHOTO - A Wells Fargo logo is seen in New York City, U.S. January 10, 2017. REUTERS/Stephanie Keith

The bank said in a filing with regulators that an expanded review found that 870 customers were incorrectly denied mortgage changes, leading to 545 of them losing their homes.

This comes after the bank in August had for the first time disclosed a calculation error in an internal underwriting software had caused 625 borrowers to be incorrectly denied mortgage loan modifications under a federal assistance program, 400 of whom had their homes foreclosed upon.

“We’re very sorry that the errors occurred and have assigned a single, dedicated point of contact to ensure that each customer is engaged with and assisted individually,” Tom Goyda, a spokesman for the company, said in an email.

The company said the expanded review is still under way and took into account customers who were in the foreclosure process between March 15, 2010, and April 30, 2018.

Goyda said the bank had contacted a substantial majority of the affected customers to provide remediation as well as the option to pursue no-cost mediation with an independent mediator.

The revelations are an additional headache for the San Francisco-based bank which is facing numerous regulatory penalties and private lawsuits, most of which stem from a sales practices scandal that touched on all of the bank’s major business units.

The bank said the issue stems from a calculation error that overstated attorneys’ fees that were needed in determining whether a customer qualified for a mortgage loan modification or repayment plan.

In August, the bank said it rectified the calculation errors and had set aside $8 million to compensate borrowers. On Tuesday, the bank, however, did not update that figure.

The bank updated disclosures on issues it discovered in auto lending, saying it had tacked on an additional $241 million for customer compensation on top of the $212 million announced earlier, related to a practice where it forced customers auto insurance that in some cases resulted in vehicle repossessions.

The bank has since discontinued that practice.

(This story corrects to say the bank added an additional $241 million for customer compensation, not increased it to $241 million in penultimate paragraph.)