The cables I was given don't fit in the broadband socket. The instructions don't even mention that, and the contents sheet doesn't mention a cable to go in there either
You need an RJ11 - RJ11 cable to connect the hub DSL socket to the socket on the right labelled broadband on the white master socket.
About 4 quid from Amazon.
You need to start at the beginning, we can't guess what your setup is.
So once again, is this a new connection or did you have Internet previously?
You don't order a Hub & phone unless just moving phone service to Digital Voice on an existing connection.
I believe it's a new connection, however, the previous owner was with BT and said it was fine.
If it helps, the router is called Smart Hub SH20A
Right, so you need the missing RJ11 cable. You can either battle BT's systems to try to get one sent out or follow @licquorice's suggestion to buy one. Screwfix , B&Q or I think I've even seen them in Asda if you want one today.
Edit: Assuming that your mother's activation date is confirmed as below. Equipment is normally sent out BEFORE activation.
Have you had an email confirmation of the start date of your service? You don't just take over an existing connection, it is a new service.
Alright then. How do I get bt to send me one? Every time I call them they ask for my phone number, so I enter it and get screeched at like I just called a demon
For the sake of £4 I wouldn't bother wasting hours of your time trying, just buy one. Your choice
Call 0330 1234 150
Bt are looking for a home phone number not mobile and if you got phone from BT then you must also have a home phone number
Of course it's also possible that this new connection will be FTTP, in which case you have the correct equipment pending the installation.