I recently started to get the 'unable to purchase' error message and now any apps i try to download to my iPhone either sit waiting for ages or wont download at all. Any else having the same issue or have a fix?
I would try going into settings, store & log out. Reboot phone & then log back in. Not sure if that will help, but it's worth a shot.
By reboot: I would try a hard reboot/reset by pressing home and lock buttons and holding until you see the Apple logo.