Wells Fargo & Co. is in the process of refunding millions of dollars to customers for adding services to their accounts without their full understanding, the Wall Street Journal reported on Thursday, citing sources.

Wells Fargo charged monthly fees for these products ranging from pet insurance to legal services that customers did not fully understand, the Journal reported, citing people familiar with the matter.

The Consumer Financial Protection Bureau is probing the matter, according to the report.

Wells Fargo (WFC) said in its latest quarterly filing that there was an ongoing review of "add-on" products across the company, adding it had started remediation efforts where it had identified impacted customers.

The lender has been trying to recover from a sales scandal for close to two years now.

It has acknowledged opening millions of accounts in customers' names without their permission, signing others up for unwanted auto insurance, charging some for a mortgage rate-lock feature they did not request and tacking other costly add-ons to accounts.