Below are some standard things you can and probably have done before calling the team.
Have you done a factory reset to the router indicated in the link below?https://help.nowtv.com/article/improve-broadband-speed
This link also shows any planned outages as well wide spread faults.
You need to call the broadband team. See link for number.
Internet outages can last variable amounts of time. It depends how severe they are, and how many people are affected.
They may only be a few hours, or they may be days; there is provision for automatic compensation if they last more than a few days. While that is nice to know, it does indicate that long outages are sufficiently common for there to be rules about this sort of thing.
If you want an extra layer of protection, you need mobile broadband as well as landline broadband. An ISP like BT will auto fail you onto a supplied mobile router at no extra cost for the duration, for instance, but it may still be cheaper to have Now and failover for yourself to mobile internet, e.g. as a hotspot on your phone. As long as you have a suitable data plan, since streaming Now sure burns up those megabytes.