Some breaks did not cost more two weeks later, promotion codes were found not to work and a website was unclear about terms.
Travellers planning to take advantage of a Black Friday holiday deal are being warned they may not be the bargains they appear.
Consumer group Which? analysed the cost of breaks advertised on Black Friday last year and found some included in the annual sales bonanza “aren’t always what they appear to be”.
EasyJet’s offering on 23 November 2018 said travellers could save £50 on 60,000 city breaks, but nearly eight of 21 trips cost less a fortnight later, Which said.
Researchers found a three-night break from London Luton to Barcelona cost 13% less if holidaymakers waited to book on 7 December.
Ryanair said a million seats were available at 25% off, if purchased by midnight, but none of the flights Which? included in its study were more expensive two weeks afterwards.
The airline issued a statement insisting it “complies fully with UK advertising laws”.
In the case of Tui, analysts found discount codes promoted as being worth up to £150 off some bookings did not work for two of the five holidays checked.
A spokeswoman for the travel firm said minimum spends apply to its promotional codes, although Which? insisted it took this into account in its analysis.
Tui added that holiday pricing is “very complex” and can fluctuate throughout the year due to a series of factors.
Airline Norwegian advertised discounts of “up to 30% off short-haul fares and 15% off long-haul fares, but the biggest saving found by Which? was just 10%.
Norwegian said the figures used in its promotion were based on fares excluding taxes and charges, but Which? claimed this was not clear when viewing the carrier’s website.
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Rory Boland, editor of magazine Which? Travel, said: “Nothing beats the feeling of saving hundreds on your next holiday, but that feeling can quickly turn to anger when you discover it would have been cheaper if you’d waited to book.
“Our research reveals that Black Friday travel deals aren’t always what they appear to be. Avoid disappointment by comparing prices and approach attention-grabbing saving claims with scepticism.”
This year’s Black Friday falls on 29 November.