Ordering via a takeaway app was on average 23% or £7.14 ($10) more expensive than ordering directly from the restaurant, a Which? investigation found.
The consumer group's analysis showed varying costs between apps, with each one charging different service and delivery fees.
Those ordering through Deliveroo were paying the most, costing an average of 31% or £9.91 more per order than going directly through the restaurant. One order — a £43.94 Deliveroo takeaway from a burrito and taco restaurant — was up to 44% or £12.29 more expensive than directly from the restaurant.
Order through rival UberEats cost 25% or £7.93 more on average.
JustEat orders were the cheapest of all app just 7% (£1.56) more expensive. The company said it offers a price promise to help ensure customers do not pay more for food they order through its app compared with ordering via the restaurant’s online delivery service, Which? said.
While restaurants generally set prices on delivery apps, they often increase the price of items when bought through the apps to cover the service fees that the apps charge them. Ordering straight from the restaurant also doesn't incur the delivery charges that ordering from a delivery app does.
Food takeaway services saw an unprecedented surge in demand as the lockdown saw restaurants shuttered for most of the year.
Of the 2,009 respondents, surveyed between 9 and 13 April, 56% told Which? they used delivery apps for takeaways or groceries. Around six in 10 people told the consumer group they used takeaway apps at least on a monthly basis pre-pandemic, compared with seven in 10 now.
JustEat was the most widely used app, with 39% choosing it. Revenues at the takeaway platform rose 54% to €2.4bn ($2.9bn,£2bn) in March this year.
"We believe our commission rates are aligned with the value we provide to our partners and we have a track record of helping restaurants prosper. It’s really important to us that our customers have a positive experience when using Just Eat," a spokesperson for JustEat said.
Meanwhile, 26% of those surveyed said they ordered through UberEats and one in five (20%) for Deliveroo.
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The majority of customers surveyed also highlighted issues with orders on the platforms and often find there is no way to effectively complain or solve issues.
The most common issues with deliveries were late arrival, cold food and missing items. Others reported ruined items, as well as orders not turning up.
Six in 10 (59%) Deliveroo users told Which? they had a problem in the last 12 months, while 53% UberEats and JustEat customers reported having an issue with an order.
A Deliveroo spokesperson told Which?: "Deliveroo always aims to offer our customers great value while also delivering sustainable growth for our restaurant partners. We encourage restaurants to set the same menu prices as they offer customers when dining in, and the commission we charge is then reinvested back into our business, paying for riders’ fees, customer services and upgrading our services for restaurants.
"Food delivery apps should do more to make the responsibilities of the restaurant and themselves clear so consumers are not caught between the two if there’s a problem with their order," said Adam French, consumer rights expert at Which?. "If customers are owed a refund for a delivery which has gone wrong, they should remember they may be entitled to a cash refund under consumer law – they don’t have to accept credit or a voucher if it isn't what they want."
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