The advertising watchdog ruled after upholding complaints against the adverts which promoted all June holidays in Cyprus for £369 and £368.
The Advertising Standards Authority acted after receiving a complaint, challenging whether the advertised prices could be substantiated.
The ASA said: “We told YourHolidays.com to provide evidence that they held sufficient stock to demonstrate availability of holidays at the advertised prices in future.”
Upholding the complaint, the authority said: “Although we acknowledged that Teletext provided a platform upon which many advertisers marketed holidays, we were concerned that YourHolidays.com, about whose holidays we received the complaint, had not been able to supply to Teletext or the ASA evidence that they were able to supply to consumers a holiday based on the search results at the listed prices.
“In the absence of such evidence, we concluded that the ads were misleading.”
Teletext told the ASA the offers did not exist until its system produced a set of results based on specific criteria searched for by the consumer.
Because consumers produced their own product using the search tool on the website, which then located matching available components in the system, the holidays did not exist prior to the complainant viewing them.
The company said holiday companies uploaded millions of offers for every combination of holiday that a consumer might search for but its technology could not load live offers for such large volumes of data.
Teletext said it had rules requiring holiday companies to show only offers with sufficient stock and that were available at the advertised price.
It said the travel industry was not able to keep records of all offers generated for a substantial period of time and that, because YourHolidays.com only promoted information from live data, it was unable directly to substantiate the offers.