Very good case study all in all. I’d suggest sending this article to AF Payments as a cold-call pitch of sorts. beeptopay.com
In the first screen though, I would like to suggest using different colors for the “Single Journey” and “Stored Value” — say yellow for Single and blue for Stored Value. The Single card as far I remember has a yellow stripe while the Stored Value is a solid blue beep card. Being consistent in all applications can help with color associations considering that English literacy is not a given.
The expiration warnings can also be given more emphasis because being caught unaware of them can affect the overall customer experience.
I really liked the minimalist iconography and the usage of color. If you want to take it up a notch, you might want to test it with people with color blindness or less than perfect vision.