When you are connected to the store WiFi, are you signed in to the store WiFi? Did you check you able to surf the web or use other apps to ensure you are getting internet data?Thanks Scrooge, I should have mentioned that I did do that. I also turned my phone off and on again, but alas no joy. A Kia Soul driver told me once he only used the web site and not the App, and I didn't try that in this instance, but if that's the case why bother having an app that doesn't work?
If you are getting data, then the next troubleshooting step is to go in to the Settings menu of the phone, scroll to Apps then locate Pod Point app. Then go to the storage section and clear the storage. Then log back in and try again. (I assume you have the latest version of the app?)
If this doesn't work then the next is to clear the partition cache of the phone. This step does not wipe your phone it only wipes any redundant files from firmware updates. This sometimes cause issues.
I assume you have a Samsung phone based on your screen shot?
Check this video on how to do it
Hope this fixes the issue. Good luck.