Ryanair has announced it is cancelling up to 50 flights a day for the next six weeks.
The budget airline said it was cutting less than 2% of all departures to clear "a backlog of crew leave".
It "apologised sincerely to the small number of customers affected" and promised to try and rearrange flights.
A statement claimed the move was to realign staff's annual holiday window and improve punctuality.
Customers complained of their holiday plans going "up in smoke" at short notice after the news broke.
Kirstin Armsden, whose flight home from France was cancelled, leaving her stranded with a hen party group that included a pregnant woman, said she was "very frustrated".
She told Sky News: "We're in the middle of France with no phone signals - currently in the nearest town.
"(There are) 15 girls on a hen party we are now having to split up to go home with the majority of the party leaving a night early which means we've paid for a villa we're not using and it's cutting into our holiday.
"A lot of the party are getting a 24 hour bus home - one of these girls is pregnant another suffers from Crohn's disease - as other flights were extortionately priced.
"We are all absolutely gutted and there's been a few tears!"
Another woman, Cathriona, said her grandparents Kevin and Kathleen Heffernan had been left stranded in Germany.
She told Sky News: "They were supposed to fly out Sunday night back to Dublin and now they have to wait until Thursday with no offer of paying for hotel or transport that is going to be needed for their extra four days.
"They are very upset as I was supposed to be moving away to college on Monday and they were coming with me. Now they are going to miss that milestone.
"They are quite distraught and upset as they have already been away for nearly a week and I think the fact they didn't even get a phone call to explain why has just made them equally angry and upset."
Ryan said his friend's birthday had been ruined after their flight to Palma was cancelled 10 hours before it was due to take off.
"We lost the cost of airport parking at Stansted, we were refunded the original cost of the Ryanair flight however the new flights costs 300 more due to last minute... We were going for my friend's birthday which was missed also - the whole experience has been a disaster."
Elien Catteeuw, who is on holiday in Italy, says: "We received a text message from Ryanair telling us that our flight was cancelled... We have to stay until Thursday now because all the other flights to Brussels are fully booked. We're worried about our hotel, we don't know if Ryanair is going to pay for it, they did not give us any information."
Robin Kiely, Ryanair's head of communications, said: "We will be doing our utmost to arrange alternative flights and/or full refunds.
"We have operated a record schedule and traffic numbers during the peak summer months of July and August but must now allocate annual leave to pilots and cabin crew in September and October while still running the bulk of our summer schedule.
"By cancelling less than 2% of our flying programme over the next six weeks, until our winter schedule starts in early November, we can improve the operational resilience of our schedules and restore punctuality to our annualised target of 90%."
A full list of cancelled flights for 16 September can be found here.