Some Oasis fans say their dreams have been "completely crushed" after Ticketmaster cancelled their orders.
They've received emails accusing them of using bots while buying tickets for the band's reunion tour.
They say that's untrue and "totally out of order".
Ticketmaster says anyone who's been contacted can appeal the decision by filling out a form.
Fans expressed their frustration after the company believed genuine fans to be bots trying to purchase tickets to Oasis Live '25 which starts on July 4.
At the time of the ticket sale, thousands of fans were left distraught as the Ticketmaster website crashed.
In cases in Ireland, fans were stuck behind 557,000 others in the queue, as sales began to dwindle for those two dates.
One fan confessed that they had bought four tickets to the concert but were told that Ticketmaster had “identified that bots were used to make this purchase.”
They told the PA news agency: “To say that we’re bots is totally out of order for Ticketmaster because we tried all day to get the tickets.”
“Our heads have been pretty battered these past 24 hours. I felt sick in the stomach. It’s a band you’ll never experience or see again and it’s been on my bucket list for years.”
“It just feels like my dreams have been completely crushed.”
Another fan confessed: “At first we thought this email was fake or a spam email, but no it was true.”
“We usually use Ticketmaster to buy our tickets… But now, how can I trust this page which is supposed to be the official page?”
The issue came as the company is being investigated over Oasis ticket sales after fans reported being shocked by standard tickets for the band's reunion tour more than doubling in price.
Fans received an email from Ticketmaster claiming bots were identified making their purchase and urged customers to fill out a form to rectify the issue.
Brothers Liam and Noel Gallagher will reunite for a comeback tour of the UK & Ireland next summer, their first time returning to the stage together since the latter quit the band in 2009.
