This fixed my problem, hope it helps others.
So I got the iPhone 5, synced my original apps from iTunes and tried the UK NatWest app.
"sorry not available at this time, please try again" or words to that effect.
Net day the same,
All week same same same.
But my iPhone 4 connected no problem.
Here's how I fixed it on my iPhone 5...
Deleted the app > rebooted the phone > re-installed the NatWest App
BOOM! It connected :)
Thanks Arthur, I was having the same problem after upgrafing from a 4 to a 5. I'd gone through deleting and reinstalling the app, but not the reboot stage. Done as you did and all's working well again.
Retrieving data ...