@Anonymous User
Welcome to the forum. Error 4008 usually indicates a problem with your payment card. You mention your payment details are correct, did you check this on your My Account > Payment Details page?
https://account.nowtv.com/payment-details
Might be worth trying on a different browser and/or device (eg try on mobile/tablet browser instead of PC or vice versa). Alternately if you have a NOW TV box you could try purchasing on that (open the NOW TV app and go to the My Account screen).
If you still have problems try popping onto live chat, explain whats happened and see if they can check things out for you.
You can get to live chat from the Contact Us page
https://help.nowtv.com/get-in-touch
(expand the Anything Else section at the bottom for options)
