Is this for broadband or TV passes?
When I was a Now TV broadband customer this is number I used to call them 0330 041 2460
If not I would then recommend using the Live chat.
1. NOW TV account & payments
2. Cancelling or renewing NOW TV Passes
3. Drop down 'How to get in touch'
4. Live Chat
FYI that I do not work for NOW, just a NOW customer trying to help