Wifi is not the internet, and with Now having carp customer service ( what you pay for is what you get) its important to get the basics right, and have some understanding of how things work before you contact support.
There are a few things you can do to help diagnose faults and in some cases fix them yourself.
If your internet is down, does the phone work - do you have a dial tone?
Is there any work going on in your area that may affect the phone lines/lines? are there openreach vehicles around?
Is there any physical damage to the phone lines, or street cabinets - if so and the damage could be a hazzard you can get in touch with openreach directly and report this , they tend to come quite quick if its a health and safety issue for the general public.
Are all the lights the correct colour on your router?
There was an issue a while back with the DNS servers that Now and Sky use, if you can change the DNS server settings in your router config - as far as i know you may not be able to do this basic function on a Sky or Now branded device , but if using your own kit then this should be simple
