Hey @Hoang-Phan
It's very easy to do in the app. Open the Public Mobile phone app and go to the payment tab at the bottom of the page. Then scroll down and click on Update Card Information. And if it fails, don't worry. Only try once if it fails. Then if it does fail, close the program. Go into your settings on your phone, then find Applications, then find the Public Mobile app and clear the cache and data. Then reboot your phone. Then log back into your phone and try again. It should work the second time if it failed the first. Trust me, this happened a few weeks back when I helped my neighbor out. Good luck to you!!
