Dodgy supermarket deals have been confusing and misleading customers, the Competition and Markets Authority (CMA) has found. In cases where retailers have broken consumer law, enforcement action could follow, it warned. The CMA findings come at the end of a three-month investigation prompted by a supercomplaint from consumer group Which? back in April. The illusion of savingThe complaint related to the existence of "dodgy multi-buys and baffling sales offers" that "create the illusion of savings that doesn't exist". It highlighted instances of shrinking pack sizes while the price stayed the same and seasonal offers where, for example, Easter or Christmas products are sold at a higher price months in advance, only to appear "on sale" during the festive period. Specific examples of dodgy deals include Asda increasing the price of a Chicago Town Pizza Two Pack from £1.50 to £2 when it went onto multi-buy sale at '2 for £3' before reverting back to £1.50 when the offer had ended. Another example included a Nestle Kit Kat Chunky Collection Giant Easter Egg which was advertised at £7.49 for just 10 days in January at Ocado but was then sold on "offer" at £5 for 51 days. Through its investigation, the CMA found that such misleading deals were not "occurring in large numbers across the whole sector" and that generally "retailers are taking compliance seriously to avoid such problems occurring". But the CMA said it will now "work with businesses to cut out promotional practices which could mislead consumers". It added: "This includes the practice of running 'was/now' promotions where the discount price is advertised as a promotion for longer than the higher price applied." It also said more could be done to reduce the complexity in unit pricing – whereby prices are stated as by weight or volume – to make it a more useful comparison tool for consumers. Unit pricingHowever, interviews with shoppers conducted as part of the investigation found that most participants stated that they were comfortable using unit pricing. When the Which? researchers asked them to select best value products and discuss unit pricing some shoppers felt "we were somehow subjecting them to a maths test of sorts". The researchers added: "These participants felt that unit pricing was simply too abstract to be useful. They simply could not imagine or visualise what 100mg of mayonnaise or 100 sheets of toilet paper might look like and therefore discounted this information as unhelpful." Which? executive director Richard Lloyd said: "The CMA's report confirms what our research over many years has repeatedly highlighted: there are hundreds of misleading offers on the shelves every day that do not comply with the rules. This puts supermarkets on notice to clean up their pricing practices or face legal action. "Given the findings, we now expect to see urgent enforcement action from the CMA. The government must also quickly strengthen the rules so that retailers have no more excuses. "As a result of our super-complaint, if all the changes are implemented widely, this will be good for consumers, competition and, ultimately, the economy."