An Auckland pizza shop owner who uncovered what is known in the retail industry as "chargeback or refund fraud" wants more businesses and consumers to be on alert.
Customers use online discount offers to order services and food - which scammers then pay for using someone else's stolen bank details.
The owner of a Domino's Pizza franchise, who did not want to be named, noticed something unusual on an invoice from May as money deducted from her account showing up as "chargebacks".
"It has never happened like this. We had so many chargebacks. I think for my shop, I had five or six chargebacks," she said.
Confused, she contacted the customers who made the bookings but they said the orders were real.
An investigation by the company found all of these customers placed their orders using third-party online advertising deals on WeChat, a social media platform popular among the Chinese community.
However, in these cases the third party was a scammer who pocketed the money and instead used someone else's stolen bank details to pay for the orders online.
When the person whose details have been stolen spotted the fraudulent transaction, their bank organised a refund from the retailer, which is known as a chargeback.
The pizza franchise owner said it meant retailers have to absorb the cost of the fraud.
"When they do the order, they couldn't tell anything wrong. All goods have been pre-paid on the internet... For the customers, it's also ok because they bought something very cheap. The problem is only the bad people got the real money."
She said it is better for people to place orders on the official website and avoid third parties.
"We're really trying to warn people not to buy things from those bad people. Protect yourself and give us a better environment."
A Domino's statement said what has happened was disappointing and the company takes the privacy of customers seriously.
"The Company has reported the WeChat scam cases and they are now the subject of a police investigation. All legitimate Domino's offers can be found on the Domino's website, Offers App and verified social media channels."
Police urge anyone who notices any suspicious transactions on their bank accounts to contact them.
The chief executive at Retail New Zealand, Greg Harford, said retailers need to be cautious about transactions made without a card being physically present.
"Chargeback fraud is a real and substantial issue for retailers, and can be hard to manage. It's part of a bigger picture of retail crime that costs the sector around $1 billion a year. It's really difficult for the retailers because the customers are generally protected from credit card fraud but merchants are often the one bearing the cost at the end of the day," he said.
"It pays for retailers to be very cautious about transactions made over the telephone or without a card physically being present. Mastercard offers an Ethoca Alert service that can help businesses manage the risks of card fraud, and has been offering a free trial of that service during July. Retail NZ strongly urges retailers to be looking at 3D secure protocols for their e-commerce site to guard against fraud."
Martin Cocker from NetSafe agreed and said credit cards are targets for fraudsters.
"It's important for businesses to have as much security and protocols as they can in place to ensure they're dealing with real people and it's important for them to have insurance and protection against these kinds of things which they can be victims to."
Cocker said consumers also need to be vigilant.
"They should always be cautious about any goods that are offered online or advertised online that are well below their normal retail price but the reality is also that there're lots of really good deals online that are legitimate. So price is not the only thing that you can use to detect a scam but it's certainly something you should be aware of."
The head of research at Consumer New Zealand, Jessica Wilson, warns people to protect their credit card information.
"Always check who you're dealing with. Look at the contact details on the website. Look for a physical address and phone number before you hand over your credit card details."
