Booking through a third-party site made it messier, so figuring out who to talk to was a headache. Ended up on https://allegiant-air.pissedconsumer.com/customer-service.html while scrolling through complaints to see what others did. That’s how I figured out which department to go through. Took a few tries but eventually got rebooked for the next day and they waived the change fee. Honestly didn’t expect it to work out, but it wasn’t a total loss.