Consumer NZ says Kiwis are still being treated unfairly with surcharges, a year after a law designed to protect them came into effect.
The Retail Payment System Act passed into law last November and led to lower costs for businesses accepting card payments.
It was expected to save businesses $105 million a year and should have meant lower surcharges for customers too.
However, Consumer NZ is concerned those savings were not always being passed on.
"Businesses shouldn't charge their customers more than what it costs them to accept a card payment. Unfortunately, as shoppers, we have no way of telling what businesses are getting charged so it's difficult to tell if we're being ripped off," Consumer NZ campaigns manager Jessica Walker said.
Those inserting or swiping a debit or eftpos card should not incur any surcharges. But contactless debit card and credit card payments could incur a surcharge.
Consumer NZ said it should not be more than 1 percent for contactless or 2.5 percent for credit cards.
In many cases, a consumer should be charged even less than 2.5 percent.
Consumer said retailers should not be profiting from surcharges, but it was concerned many were.
"Big businesses usually pay lower fees for accepting card payments because of the volume of transactions they process, and this should be reflected in the surcharge passed on to the customer. If, for example, you pay your power bill by credit card, you're only likely to have to pay a surcharge of around 1 percent, or less.
"This lower surcharge is good to see, but the same can't be said for all businesses."
Consumer had received numerous complaints about Ticketek.
Earlier in the year it contacted the event ticket seller about its payment processing fee of up to 3.5 percent.
"We asked Ticketek why its payment processing fee was so high. Ticketek told us it had reduced its surcharge to a standard 3 percent and would lower it further. However, we're still receiving complaints about Ticketek charging 3.5 percent. We think this is excessive," Walker said.
"In our view anything higher than a 2.5 percent credit card surcharge, or a 1 percent contactless debit card charge could be excessive."
Another example was a patient of an Auckland dental practice who said she received a $5 surcharge for a contactless payment of an $80 dental bill.
"That's a whopping 6.25 percent surcharge," Walker said.
Some parking apps were also reportedly charging in excess of 8 percent, she said.
Consumer had received more than 80 complaints from people who believed they had incurred excessive surcharges.
"If you come across a surcharge that you think is excessive, ask the business why it's so expensive. If you're not happy with their explanation, make a complaint to the Commerce Commission. Ultimately, we want to see an end to excessive surcharging," Walker said.
Both the Banking Association and Payments NZ told RNZ it was not their place to comment on surcharges.
RNZ also attempted to contact Retail NZ, Ticketek and the Commerce Commission, but has yet to hear a response.