If on the day your deferred payment is due, the credit card used is declined, you can use the steps in this guide to add a new card, thus avoiding an auto-cancelation.
Here's how to modify the credit card
Navigate to your ‘Trips’ screen and select the reservation to change. Click ‘Change Reservation’
Once the change reservation screen opens, you need to amend the URL in the browser. Scroll to the end of the URL and look for the text in blue as shown in the URL example below.
The URL looks like: https://www.expedia.co.uk/trips/bfc755a2-8f25-59d2-b5c3-e52829f3ed38/ordernumber/9159547019446/orderlinenumber/55471a5e-14c3-4433-adb3-27193009342b/change?rfrr=HOT.ITIN.RES.CHANGE
Once you have the UR, replace the text shown in blue above with /change/creditcard and hit ‘enter’ to accept the URL changes.
The credit card change screen will display, allowing you to amend the payment details.
The new URL should look like this: https://www.expedia.co.uk/trips/bfc755a2-8f25-59d2-b5c3-e52829f3ed38/ordernumber/9159547019446/orderlinenumber/55471a5e-14c3-4433-adb3-27193009342b/change/creditcard