Invalid voucher code please help
Did you attempt to apply the voucher code on your playback device or on the nowtv website ?
If using the website, maybe try a different internet browser, clearing your cookies and disabling your ad blocker.
Also have a read of this help guide for pointers.
Where did you purchase the voucher from ?
If it was a nowtv gift card purchased directly from a shop was the code activated at the till ?
Maybe if you are still struggling, then try live chat.