Wells Fargo, the largest mortgage lender in the country, portrays itself as a stalwart bankthat puts customers first. That reputation shattered in September, when it was fined $185 million for illegally opening as many as 2 million deposit and credit-card accounts without customers’ knowledge.

Now four former Wells Fargo employees in the Los Angeles region say the bank had another way of chiseling clients: Improperly charging them to extend their promised interest rate when their mortgage paperwork was delayed. The employees say the delays were usually the bank’s fault but that management forced them to blame the customers.

The new allegations could exacerbate the lingering damage to the bank’s reputation from the fictitious accounts scandal. Last week, Wells Fargo reported declining earnings. In the fourth quarter, new credit card applications tumbled 43 percent from a year earlier, while new checking accounts fell 40 percent.

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