Air Canada has a new booking system, and some of its customers aren’t happy with it.

As of Friday morning, some customers were still reporting issues on social media with booking flights or modifying existing reservations following a migration to a new system on Tuesday.

In a tweet early Friday, Air Canada said “the situation is being monitored closely” and assured the issues would be fixed.

The airline warned customers last Monday they would not be able to make or modify reservations as of 8 p.m. until the middle of the next day while the migration to the new system was taking place. But customers were reporting issues throughout the week.

On its website last Tuesday, Air Canada said it’s “business as usual” with the new reservation system in place. However, the airline did acknowledge it was experiencing some technical issues related to the migration on Friday.

“As with any IT project of this magnitude and complexity, some temporary issues are inevitable and we are working hard to resolve these as quickly as possible,” a spokesperson for Air Canada said in an emailed statement to BNN Bloomberg.

“In a relatively small number of cases, some customers are unfortunately encountering technical issues and, at times, longer call center wait times, Overall, however, the new system is functioning as expected”

The airline added it has continued to operate its schedule normally despite the issues with its booking system.