Cannot connect to WiFi

[Issues1]

Have checked the signal etc on sky app and says it's fine but none of our devices can connect to the WiFi . The signal has got progressively worse over the last few months. Also phone signal for all our phones has been terrible for about 6 months and seriously considering changing back to Vodaphone at this point. I did report this several weeks ago and there has been no improvement 

[Issues1]

When the internet is working it does not even manage to cover the whole house which is a standa d 3 bed, not a mansion!! I want something actually done to improve this shocking service!!