Thanks for posting, sorry to hear this. Can you try changing your password for us even though it works on laptop. Also can you try deleting the app and then re-installing on your iPhone and also try signing in via 3/4g and then revert back to your wireless network.
Let us know how you get on.
NOW TV Team
Same/Similar problem... can logon via a browser on my laptop but, logon id/pw not accepted via the Now-TV box.
Followed the guidance - went online via a browser, reset the pw, logged on to the Now-TV box, watched one episode of a show. Left that site, watched a show from the BBC, went back to watch something on Now and was again, challenged for the uid/pw but, was rejected.
What's going on here?!?