Judging by previous posts, the pass code may be sent to the main email address you have linked to your nowtv account. Make sure the email address is correct via 'my account>personal details' at the top of this page. Check your email account to make sure no nowtv messages have been considered as junkmail and accidentally thrown into any spam folder. You should be able to activate any pass via 'my account>passes and vouchers'.
If you definitely did not receive any pass code then you may need to persevere with the online chat or send a message. I don't see why at least one member of staff should not be able to help, or at least give a reasonable explanation as to why they cannot.
https://help.nowtv.com/contact-us/managing-my-devices
