I am having the same problem. My account is linked by BT and my box just died so should be able to get now tv on smart tv but it won't recognise my account. Can sign in on the laptop but I am not receiving password reset emails!! Did you ever get this sorted?
Follow these steps and you will be able to speak with an advisor
I was able to reset my password this way as they sent me the link.
1. Go to the NowTV home page
2. Scroll down to the bottom of the page and select complaints
3. Click NowTV Passes
4. Click cancelling my passes and then click I still want to complain
5. Click chat online and you will be connected to an advisor
Ask them to help you reset your password and they will do it quickly. You will need to confirm your name and email address. I know these steps are a lot when the email to reset your password should be sent. But seeing as the email isn't coming through and I tried myself about a dozen times. Then this will at least resolve the issue