American travellers preparing for the busy Thanksgiving travel rush received a rude surprise in their inboxes last week.
"There has been a change to your upcoming flight" read the foreboding subject line.
The email that was received by thousands of passengers with Frontier Airlines directed them to call the airline's "rebooking hotline" to discuss next steps.
Within minutes the call centre was in gridlock under the weight of incoming calls from travellers, concerned about their holiday plans. Some passengers reported being forwarded straight to voicemail.
The customer assistance Twitter account didn't fare any better, which was immediately swamped by anxious tweets. "Can we get an update as to what is going on with these emails cancelling flights?" wrote one concerned traveller who called the emails "very unprofessional."
Frontier eventually admitted there had been a mistake By 10pm Eastern Time, although travellers complained
The airline apologised for the "technical problem" which had caused the email to go out to customers. Frontier urged passengers to check their flight details on their website to confirm their travel status.
A spokesperson for the airline told USA Today that the source of the email was under investigation.
However this will be small comfort to the travellers who had already made backup travel arrangements.
"I was terrified because these (flights) are coming up in a few days," Steven Harms told USA Today, as considered rebooking his family's travel last minute.
"If we had to rebook it would be a really tough situation just because it's the holiday."
A report by Smartertravel.com found that air fares over the Sunday before Thanksgiving were up to 70 per cent above average, even more when booked last minute.