I am able to access Facebook using my Three mobile data but NOT courtesy of Talktalk WiFi.
I want nothing to do with your Homesafe technology and I have complained about your interference in completely innocent browsing in the past. If this continues it will contribute to whether or not I leave or stay when my current contract expires.
There are just too many things going wrong with this company just now for me to expect to find any reasons to stick with it a moment longer than is absolutely necessary.
If you're not taking advantage of the security features of HomeSafe / KidsSafe then test with the workaround of using a different DNS setting in the router.
Here is the advice and router setup needed for using a Third Party DNS (Click here)
Try Quad9 and Google DNS: Primary - 126.96.36.199. and Secondary 188.8.131.52. or a DNS of your choice.
Hopefully the incident won't last too much longer, but that advice from Gondola is great in the meantime.