Thousands heading off at the start of the school holiday this weekend faced bad deals.
Forexchange at Cardiff Airport was handing out just 87 cents for £1 – despite the rate being 1.11 euro to £1.
At Moneycorp at Stansted Airport in Essex customers were given 90 cents for £1 after £4.99 commission.
At Gatwick, Birmingham, Heathrow, Manchester and Glasgow passengers got one euro or less for £1.
In contrast, the Post Office website offers those exchanging over £500, 1.09 euro for £1.
Last week Liberal Democrat leader Vince Cable called for companies to be investigated.
He said: “Holidaymakers have been ripped off. Their week in the sun is already 20 per cent more expensive due to the weak pound, but these operators are cashing in.”
FairFX’s Ian StraffordTaylor said: “The pound has been subject to volatility since the Brexit referendum and some currency providers look to be taking advantage.”
In summer 2015 Britons got around 1.41 euros for £1.
Victoria Willis, of Harwich, Essex, flew from Stansted to Rhodes in Greece on Friday.
The 16-year-old got just 66 euros for the £75 she cashed in at Moneycorp, leaving her feeling “a little bit ripped off”.
Ben Simmonds, 26, of south London, received 70 euros for £80 from the same desk.
An employee had told him to “brace himself”.
Moneycorp, which made £11.6million post-tax profit in 2015, said the rates are down to operating costs at airports and encouraged customers to pre-order online.
Forexchange said: “We are working closely with Cardiff Airport to improve our currency rate strategy.”