Which? urges action on 'misleading' supermarket prices
The consumer body Which? has called on the regulator to act over "confusing and misleading" supermarket prices.
It has launched a "super-complaint", a legal move which means the Competition and Markets Authority (CMA) must respond within 90 days.
Which? said it had repeatedly exposed the tactics, but that "these dodgy offers" remained on the shelves.
Industry body the British Retail Consortium (BRC) said it did not accept the implications of the complaint.
"The examples set out are very specific in nature and are not in any way indicative of broader systemic problems across the retail industry," said the BRC's Tom Ironside.
"With thousands of products and special offers in store every day, errors may from time to time occur. However, these are rare in nature and are resolved quickly by the retailer concerned," he said.
However, he said the BRC would "examine closely the content of this super-complaint".
The main concerns identified by Which? are:
- confusing and misleading special offers
- lack of easily comparable prices because of the way unit pricing is being done;
- and shrinking pack sizes without any corresponding price reduction.
Analysis: Kamal Ahmed, BBC business editor
The complaint by Which? goes to the heart of what is called "confusopoly" in mature, western markets.
The word was first catapulted to fame by Scott Adams, the man behind the gloriously funny cynicism of Dilbert, the cartoon strip which punctures all that is bad about the management speak of "customer focus" and "cascading management" techniques.
He wrote in 1998: "In the future all barriers to entry [in major markets] will go away and companies will be forced to form what I call confusopolies.
"Confusopoly: a group of companies with similar products who intentionally confuse customers instead of competing on price."
In the past, the energy and mobile phone sectors have been attacked for bamboozling consumers with impenetrable tariffs and deliberately opaque special offers.
Richard Lloyd, executive director at Which?, said: "Shoppers think they're getting a bargain, but in reality, it's impossible for any consumer to know if they're genuinely getting a fair deal.
"We're saying enough is enough and using one of the most powerful legal weapons in our armoury to act on behalf of consumers by launching a super-complaint to the regulator.
"We want an end to misleading pricing tactics and for all retailers to use fair pricing that people can trust," he said.
About 40% of groceries in Great Britain are sold on promotion, according to retail research group Kantar Worldpanel, so consumers could be losing hundreds of millions of pounds, even if only a small proportion on offer are misleading, said Which?.
Which? is one of five consumer bodies that have the power to launch a super-complaint. The last time it did so was in 2011, when it asked the regulator at the time, the Office of Fair Trading, to investigate excessive credit and debit card surcharges.