Travellers who are considering flying with TUI, easyJet, and several other carriers have been warned “don’t fly without” by industry experts. The summer season may have come to an end, but many people are clearly still keen to get away, with airports across the UK remaining fairly busy.

With the October half-term approaching, it’s expected that numerous families will be heading overseas in search of some winter sunshine. And consumer advocacy group Which? has issued an update to people with plans to board flights.

In a post shared on Instagram, Which? experts said: “Searching for a customer service number for easyJet, Ryanair, or Wizz Air? It’s not as easy as you’d think. Some budget airlines bury their contact info deep”. A graphic included added: “Need to know: Don’t fly without these contact numbers” before listing the respective numbers for easyJet, Ryanair, Wizz Air, British Airways, Emirates, Jet2, KLM, Norwegian, Tui UK, and Virgin Atlantic.

Which? is known for its travel guidance, as well as money-saving tips and more. Earlier this year the testing, reviews and advice organisation shared how passengers may be able to bag an upgrade from economy class.

It found premium economy fares to be “typically at least twice as expensive” as an economy ticket, and said that myths on how to be upgraded, such as wearing nice clothes or giving a gift to cabin crew, are simply untrue. An article added: “Free upgrades, while rare, do happen, but the airline you choose is crucial.”

It added that 7% of Qatar airlines passengers surveyed were given a free upgrade, with 5% for KLM, 4% who flew Emirates, and 3% of BA and Virgin Atlantic passengers. 2% of those who flew with American Airlines said they had had a free upgrade, with 1% for Singapore Airlines, and 0% for Lufthansa, Qantas and Tui.

Which? added: “Most passengers who are upgraded will likely be a member of the airline’s loyalty/air miles club, which is free to join.” Using air miles can be a good way to upgrade, and flying isn’t the only way you can earn them as some credit cards give you points every time you spend, Which? added.