Halfords has been told to remove "misleading" pricing from its website after overstating savings on certain products.
The car and bike accessories retailer listed two car radios in July, claiming savings of £20 on each one.
%VIRTUAL-SkimlinksPromo%But a complainant noted that the radios had only just been released, and challenged whether the savings claims could therefore be substantiated.
Halfords said the products went on sale at the original prices on June 17.
It had not intended to make any references to the higher prices in advertising because fewer than 28 days had passed before the sale price took effect, but said they had appeared in error.
The Advertising Standards Authority (ASA) noted that industry best practice recommended that comparative prices should have been available for at least 28 consecutive days and last offered no more than six months earlier.
It said the evidence supplied by Halfords was not sufficient to support the claimed savings for either model.
The ASA said: "We considered that Halfords needed to provide documentary evidence showing that the items had been sold at the higher prices listed in the ad for a sufficiently long period to ensure that they were genuine retail prices and that consumers were not misled by the savings claims.
"Because they had not done so, we concluded that the claims 'was £169.99' and 'was £149.99', and the associated savings claims, had not been substantiated and were therefore misleading."
It ruled that the claims must not appear again in their current form.
A spokesman for Halfords said: " This was a genuine mistake. We work hard at all times to observe the relevant guidelines and to provide our customers with accurate and helpful information."
Advertising's most sexist ads
ASA raps Halfords over pricing
"A woman is only a woman but a good cigar is a smoke".Only a woman? Feminists would take issue at the "only" adverb, and the idea that any human being of either gender is inferior to a cancer-inducing product from Benson & Hedges.
Don't blame the ad men completely. That ad tag line is actually the evil work of one Rudyard Kipling. From a poem he penned called "The Bethrothed".
Now this is a creepy ad: "I have created a playground for men's hands." Armando Ghedini created wigs "for other men who adore women". This wig was also wash'n'wear. Nice.
The thoughtful signor Ghedini had also designed a wig to be combed in any direction, "for men to tousle". Men, he said, become "inspired" by women who wore it and women, Ghedini added, were grateful.
VW advertising has often been self-deprecating and clever. In 1960s America their ads were phenomenally successful, persuading thousands of Americans to ditch large thirsty home-made offerings for the company's cramped, noisy but economical Beetle.
Their ads flattered the intelligence of the American middle class. But this ad depicing a bashed-up VW bug? "Sooner or later your wife will drive home one of the best reasons for owning a Volkswagen". Not their female customers, clearly. What were they thinking?
Similarly, Easyjetalso thought that a pair of ample breasts would be enough to help ticket sales. This ad dates back to 2003 when George Bush, Dick Cheney and Tony Blair were getting very animated about those hard-to-find weapons of mass destruction.
This particular ad garnered around 200 complaints to the Advertising Council and also escaped any ticking off. And plenty of publicity of course. It all worked out beautifully for Easyjet. Tits away, Stelios.
Car manufacturers and cigarette companies are regular sexist offenders. Here Italian typewriter maker Olivetti peddles the idea that young women are passive, servants ready to transcribe boardroom minutes at a moment's notice.
Where are Olivetti now in the global brand firmament?. Join the Olivetti girls. At ease, ladies, please.
Melon distributor F.H.Hogue of California thought his melons were pretty buxom and wanted to spread the word. Ho-ho, Mr Hogue.
There are plenty more examples and we'll be looking at more anther time. In the meantime let's leave with a woman knowing exactly where she should be (in the home, honey).
Here is a 1970s shoe ad from a brand called Weyenberg. You may find it hard to track down a Weyenberg shoe today however.
However, not all car makers followed such a well-worn patronising path. Back in the 1970s Honda in the US reversed the idea that women always needed cars with simple, easy-to-drive automatic gearboxes.
Despite offering both a manual and auto gearbox, neither was "a women's car" Honda stated firmly. Note the jaunty hat and jeans. A stab at selling to the US lesbian community? Or an independent straight girl fed up with stereotypes. Good for Honda.