Nearly $500 billion traded hands last year on Zelle, a mobile payment application.

With so much cash moving through the system, it’s no surprise scammers have taken note.

The Zelle network is owned by a group of banks. But as WGN Investigates found, those financial institutions don’t always ride to the rescue when customers lose money to fraud.

Take the case of Debbie Shepard-Polak, a suburban landscaping company owner. She recently lost $4,600 in a sophisticated scam involving Zelle.

It started with a text asking if she spent $1,092 at Wal-Mart.

Believing the text was from her bank, JP Morgan Chase, she responded no. Then, her phone rang.

“The lady on the other line knew I had gotten that text,” she says. “She’s like, hang on, I can help you.”

Still on the phone with who she believed was a Chase representative, Shepard-Polak received another text asking if she authorized a $4,600 payment via Zelle.

Logging into her Chase account, Shepard-Polak followed the woman’s instructions.

She believed she was reversing that fraudulent Zelle payment when in fact it was just the opposite.

“That’s where the scam was,” she says. “She took my money. It was gone.”

A federal law covering electronic transfers requires that banks cover losses if the transactions are, determined to be “unauthorized.”

But in Shepard-Polak’s case, Chase ruled she “authorized” the payment, even though she was tricked into making the transfer.

Peter Tapling, a payments consultant, says he’s not surprised.

“Zelle is not a credit transaction,” says Tapling, managing director of PTap Advisory LLC.

“It’s money out of the bank and it’s irrevocable,” he adds. “[And] that irrevocability is what causes this misunderstanding between the financial institution and the customer.”

The Consumer Financial Protection Bureau says when a consumer informs a bank that money was stolen from an account – the burden is on the bank to prove the transfer was authorized by the consumer.

A Chase spokesman says the bank determined that’s what happened in the case of Shepard-Polak, despite her objections.

“Unfortunately, scammers target consumers from many banks,” the spokesman says. “We urge all customers never to share their banking password or send money to someone who says it will prevent fraud on their account. Bank employees won’t call, text or email customers asking for this, but crooks will.”