I just purchased a flight ticket operated by Vietnam Airlines on Expedia, but I didn't notice the section on entering the passport number on the payment page on Expedia, and found that I completed the purchase without entering my passport number.
The problem was that I recently renewed my passport, and didn't edit my passport number on Expedia in advance.
So the ticket was purchased with my wrong passport number. In this case,
Can I still change the passport number only or do I have to book a new flight ticket with the old one being a waste?
Is it free of charge to change the passport number if it is possible? I got charged in Spring Airlines recently...
Is it Expedia or Vietnam Airlines that I should contact?