You can also try with PM app (with locator on). If via website, you can also try a different web browser, clear cache or incognito mode. Or try a different credit card (if available).
Here is some more information:
Log out of your account and relog in before updating your card
If you attempted to update the same card multiple times please try again tomorrow or today with a different card as there is a daily limit on update attempts for security purposes.
Make sure that your credit card postal code matches your phone number's area code
As always, please be sure that you are inputting the correct card details
