According to this link subtitles are only for Entertainment and Movies on Now TV.
Got a NOW TV Box or NOW TV Smart Stick? Just start watching the movie or show, and press the star (*) button on your NOW TV remote.
Alternatively, use the arrow buttons on your NOW TV remote to select the speech bubble symbol in the bottom right-hand corner of the screen.
If I were you I would head onto Live chat to confirm and if needs be raise a complaint. Just make sure you click "chat online" within the green box.
Alternatively you can send an email to the address in the below picture.
FYI that I do not work for NOW, just a NOW customer trying to help