Holidaymakers struggle to obtain accurate information from travel firms about financial protection, an investigation has found.
Staff at travel companies have a "lack of knowledge" about what is covered by the Atol scheme, research by Which? Travel magazine revealed.
Posing as potential customers, the publication made 80 calls to eight travel firms, asking a variety of questions.
British Airways and lastminute.com exaggerated Atol protection, with the former incorrectly telling researchers "on several occasions" that they would be covered despite only purchasing a flight.
Thomas Cook employees performed "particularly poorly" getting less than half (45%) of the answers correct, according to the report.
In eight out of 10 cases, the tour operator's staff could not confirm that customers are Atol-protected if they book a flight and hotel at the same time, or book a hotel the day after buying a plane ticket.
The Atol scheme ensures travellers do not get stranded abroad or lose money if a company stops trading.
UK-based companies must protect bookings consisting of flights and accommodation or flights and car hire.
More than 1.5 million travellers had their plans thrown into chaos in recent weeks because flights are not going ahead as planned.
Some 860,000 customers held bookings with Monarch when the firm collapsed on Monday, and around 700,000 passengers were affected when Ryanair cancelled flights after it mismanaged pilots' annual leave.
The investigation by Which? Travel found an online post by Ryanair wrongly stating that its subsidiary, Ryanair Holidays, was a member of Atol.
Ryanair Holidays is run by a German company and is part of a financial protection scheme in that country, according to the research.
The post has since been amended by Ryanair, but it is "still not clear how a claim to the German equivalent of Atol would be made", Which? Travel warned.
The magazine's editor Rory Boland said: "Given the recent chaos caused by Monarch going into administration and Ryanair's flight cancellation shambles, it's just not good enough that travel agents don't understand the rules around holiday protections - especially when they are exaggerating the cover on offer.
"Atol-registered companies need to improve the accuracy of the information they are providing to their customers, and companies registered abroad must do more to inform customers in the UK about what protections they will be covered by."
Ryanair chief marketing officer Kenny Jacobs said: "Ryanair holidays complies with all legal and regulatory requirements including EU provisions relating to insolvency protection.
"Ryanair Holidays' application for Atol protection remains ongoing. We expect the CAA (Civil Aviation Authority) to grant Atol protection shortly."
CAA chief executive Andrew Haines said he was "furious" with Ryanair last week because it was not telling passengers they are entitled to be re-routed by other airlines following its flight cancellations.
The airline later agreed to implement measures to ensure passengers are "fully aware" of their rights.