Booking flights through online travel agents can end up costing customers hundreds of pounds more, new research suggests.
Which? carried out 28 spot price checks, comparing the amount travellers would pay on popular routes when booking directly with an airline or with online travel agents (OTAs) such as eDreams, Gotogate, Kiwi and Opodo.
In all cases, it was cheaper to book directly with the airline if adding on extras like hold luggage or making a seat selection.
This was despite the headline prices offered by OTAs often being marginally cheaper.
In one example, Which? was quoted £556 by eDreams for a return flight from London Gatwick to Orlando, flying with British Airways.
This was the cheapest price on offer for the route, just £2 less than if a traveller booked with British Airways directly.
Once hold luggage was added and a seat chosen, the price quoted by eDreams shot up by £258, to £814.
The same flight booked directly with BA, with the same extras, would have been £712 - a saving of £102.
Similarly, a Ryanair flight from Stansted to Athens was priced at £104 via Opodo, £3 cheaper than Ryanair.
Once researchers added one 20kg hold suitcase, one 10kg cabin bag with priority boarding, and chose a seat, the price quoted by Opodo more than doubled, coming in at a grand total of £261.
Booking with Ryanair and making the same selections, £195 was quoted - £66 less.
Ryanair has been complaining about OTAs for some time, and now charges customers who use them about 30p to check-in online.
OTAs argue that they offer customers more choice by allowing them to view flights from different airlines at the same time.
Customers have also accused OTAs of offering substandard customer care.
In a recent survey of flight booking sites, no company achieved more than three out of five stars for customer service.
Kiwi.com charges approximately £17 per person to access higher caller priority and email support, among other perks such as free trip changes.
If you choose not to pay, you’ll be low priority when calling, and could face additional charges of up to £30 for any additional services, compared to £10 if opting for the ‘plus services’ option.
Rory Boland, Editor of Which? Travel, said: “It’s easy to be tempted by headline airfares from online travel agents that save a few pounds but you are always better off booking directly with the airline.
"Not only is it likely to work out cheaper in the end, but in the event that something should go wrong, it will be clear where the responsibility lies.
“If you’re looking to find the best value prices, flight comparison sites will always be the preferable option for finding the cheapest seats.
"Likewise, if you’re keen to book as a package and add accommodation to your flight booking, Which? would always advise using a reputable package holiday firm.”
A spokesperson for Opodo noted that it helps customers compare prices between airlines, and that comparing it with airlines was "misleading".
“Opodo is able to create over 9 billion different flight itineraries from 700 global airlines, giving consumers more choice and flexibility to create their bespoke trip on one platform, as opposed to being limited to booking the only option given by one single provider," they said.
“It is also totally normal for prices to be different between airlines and OTAs and this is the same across retailers in all industries - supermarkets have different prices to grocery wholesalers, for example. There isn’t anything untoward about this, OTAs simply offer different options for travellers to consider.
“Comparing the offer of an airline with an OTA in such a one-dimensional way is misleading, it doesn’t give customers an accurate picture of the merits of different methods for booking travel and this restricts travellers’ ability to make informed choices.”
The Mirror also contacted eDreams, Gotogate and Kiwi for comment.
