Some major hotel chains are potentially misleading consumers with “bait pricing” offers of cheap rooms while in reality making only a few available, a study suggests.

Which? said the “cynical” pricing practice disappointed customers but could still boost sales for hoteliers, as consumers were far more likely to make a booking despite not finding the advertised deal in order not to waste the time and effort they had already invested.

In one example, Which? examined a promotion run by Travelodge advertising hotel rooms in London “from £55”, and outside of the capital “from £39”, enlisting a sense of urgency and stating: “Book your room now! Book early so you don’t miss out! Rooms from £55. Book online today. Book for tonight.”

Which? researchers collected thousands of prices for 138 participating Travelodge hotels over a six-month period to see how many rooms were actually available at the advertised price.

Overall, 15 hotels Which? checked had less than 10% of nights available at the advertised price.

Our price messaging fully complies with Advertising Standards Authority requirements and we remain transparent with our customers about costs

During July, Travelodge was advertising stays in King’s Cross in London “from £55”, but when Which? checked availability for the six months from that date, it only found three nights available at that price – and all were Sundays in January.

The Travelodge London King’s Cross Royal Scot down the road offered just 8% of nights for £55, with the majority (64%) costing upwards of £100 and one night reaching £220.

Which? did find some locations gave a better chance of finding the advertised deals, including at Travelodge Burton, where 66% of nights the watchdog checked were £39 or below.

Travelodge said its adverts fully complied with Advertising Standards Authority (ASA) guidelines.

Advertising guidance says retailers must be clear with consumers that stock is limited, and the availability of a product must be “spread evenly across the advertised travel period”.

Retailers must also monitor stock and withdraw or amend advertising once a product sells out at that price.

In July and August, Accor ran a 15% off member exclusive offer for its French hotels on Facebook, advertising rates for a Mercure property near the Eiffel Tower “from £129” a night, based on a two-night stay.

However, Which? checked on the last day of the sale to find no nights available at this price over the whole 64-day travel period. Instead, the cheapest room cost £142, and the majority of nights (62%) cost well over £180 and peaked at £252.

In all, 15 of 19 Accor hotels advertised had no nights at the promotional rate when Which? checked on the sale’s final days.

Which? found Hilton also continued to promote some hotels at a 20%-off sale rate after they sold out of rooms.

Which? checked 13 of the participating hotels and found good availability at most, but found no nights available at Hilton’s historic Grand Hotel des Sablettes Plage – advertised as “from £133” – for the remaining 18 days that the offer was valid. Instead, the cheapest available night was £180.

This year, the ASA has taken action against Premier Inn and Eurostar for misleading consumers with sale offers.

Which? said it had shared its findings with the ASA, and is also calling for a review of trading standards to ensure adequate enforcement of consumer protection laws.

Which? Travel deputy editor Naomi Leach said: “All too often we see holidaymakers misled by too-good-to-be-true sales, where hotels reel consumers in with the promise of a great deal, only for it to be almost impossible to make a booking at the bargain rate.

“It is completely unacceptable that holiday companies feel they can push the boundaries, and it’s clear that stronger enforcement of consumer law is needed to ensure businesses know that misleading pricing will not be tolerated.”

Travelodge said: “Travelodge fully complies with ASA guidelines and is confident in its data, advertisements and offers. We have reviewed this advertisement in detail and the number of rooms available at the low price of £55 is well over the ASA minimum requirement.

“While room availability at individual hotels is affected by customer booking patterns and local circumstances, our price messaging fully complies with ASA requirements and we remain transparent with our customers about costs, supported by our best price finder tool on our website.”