@Robyn136 Actually, this same scenario happened to me. I made a reservation in early March and chose the Pay Less Upfront option, meaning I paid half when reserving with the remainder to be paid at a later date (today). After the first payment I was notified by my bank that there had been fraudulent activity on the card I used to make the first payment to Airbnb. (The fraudulent activity had nothing to do with Airbnb.)
My bank cancelled the original credit card account and issued a new card. I took screen shots to show you how Airbnb handled the situation when they tried to charge the original, now cancelled, credit card:
[Reservation number hidden]
When the charge for the second payment did not go through, I got this message:
So I clicked on the "submit payment now" link and added the new credit card number:
The process was so easy a 7th grader could follow the steps.
One thing that may be confusing is that by adding a new credit card to one's Payment Methods won't automatically be charged in this type of situation. One must actually enter a new card number in this manner in order for payment to be made.
I hope this is informative!