Consumer NZ is warning almost half of New Zealanders could have breached their bank's terms and conditions by using a popular payment method.
POLi enables people to make a payment directly from their bank account, without incurring fees from a service provider like Visa or Mastercard.
However, Consumer investigative writer Ruairi O'Shea says POLi needs the user to provide their bank log-in details so the merchant can generate the payment.
And this could affect a customers' bank protection if caught in a scam.
POLi is used by 1.6 million people - 40 percent of bank customers and has done 45 million transactions since 2008.
Ruairi O'Shea from Consumer joined Kathryn to explain what he found.