@bcj
there has been some issues with credit card update If it does not work the first time and you don't need to make a payment urgently, wait 24 hours and try again. Also, please try using BOTH browser and Public Mobile App, some reported they have success after trying with the different method to access My Account.
When you test with browser, try using Incognito mode
When you test with app and if app was already installed, uninstall it first, clear the cache for your default browser on the phone, then reboot the phone and reinstall the app
Also, while PM is not sending name/address info to credit card for posting payment, it looks like they still have some kind of validation now when updating new credit card. So, make sure you have the correct address and postal code on your My Account's Profile and match those on your credit card. Also, check the name on your profile. If you have a very long name, maybe try shortening it with initials.
And, if you need to make payment urgently to resume service, you can get a voucher from SDM/London Drug/711/Shell and then load the voucher using *611 on your phone (or 1.855.4PUBLIC from another phone) to resume service first and then try updating the card again later
If nothing works, best to open ticket with PM support:
