Travel agencies reported a leap in exchange sales around the vote, with online ordering services suspended due to unprecedented demand.
Holidaymakers began “panic buying” foreign currency after the pound dropped to its lowest rate against the dollar since 1985 following the vote to leave the EU.
Thomas Cook and Hays Travel halted their click and collect online ordering services as demand soared from clients trying to get the best deal during Thursday night and Friday morning.
Cook temporarily pulled its click and collect cash service after online orders rose. Euros were available only through high street branches. The service was operating as normal on Monday.
A spokeswoman said: “We have a good supply of euros across our network. This follows a temporary period of being offline due to unprecedented demand for currency after the referendum.”
Hays reported record sales of foreign exchange last Wednesday and Thursday ahead of the referendum result.
Managing director John Hays said customers logged on to secure currency at Thursday’s rate while the pound was plummeting.
He said: “Savvy people were securing currency early and we experienced a few problems online with people buying currency between 2am and 7am on Friday morning.”
Hays suspended its service on Friday and said it would remain switched off “until the economy stabilises”.
He declined to reveal how much money was lost as a result of honouring the rate, but described it as “a minor sum of money”.
Miles Morgan Travel owner Miles Morgan said the agency chain kept selling out of euros.
“I was not surprised by what was going on in the week because the rate was climbing,” he said.
“But I was surprised by strong sales on Friday and Saturday. It tends to indicate people are worried the rate will drop lower.”
Advantage Travel Partnership managing director Julia Lo Bue- Said added: “Bureaux de change sales are up: that may be panic buying.”
The pound’s value fell from €1.31 on Thursday to €1.21 on Tuesday.