The Consumer Financial Protection Bureau said Friday it filed a complaint against three of the country’s largest banks and the operator of Zelle, the most widely available peer-to-peer payment system, “for allowing fraud to fester” on that network.CFPB estimates that hundreds of thousands of customers of JPMorgan Chase, Bank of America and Wells Fargo have lost more than $870 million since Zelle launched seven years ago.Those three banks co-own Zelle, along with four other big U.S. banks: Capital One, PNC Bank, Truist and U.S. Bank.“The nation’s largest banks felt threatened by competing payment apps, so they rushed to put out Zelle,” said CFPB Director Rohit Chopra in a statement. “By their failing to put in place proper safeguards, Zelle became a gold mine for fraudsters, while often leaving victims to fend for themselves.”CFPB notes that customers who filed fraud complaints “were largely denied assistance, with some being told to contact …