I am having the same problem - I have 4 devices, have deleted 2 (confirmation pop-up appears) but it is still showing 4 devices. As a consequence I can't add a new device. Looks like people need to receive an email from Now TV to sort. Is there a quicker solution?
I'm having exactly the same problem I've tried to delete my old PS3 as a device (tried both on a mac and on my iPhone) and it says that it has been deleted - but then still appears in the list. It seems like this is happening to few people. If there a solution that doesn't involve the now TV team sending out emails to inviduals, it might be worth posting it? I guess that there isn't though.
Any help would be much appreciated