Broadband Internet & ISP Recommendations?

Trying to order some more wifi discs for my BT Broadband (BT Complete Wifi - their equivalent of a mesh network). I've got one disc but I need another 2 to get the flat completely covered as a couple of rooms are "poor" (they let you have 3 max).

Can't just order them online, no, that would be too easy.

• Directed to use the app (which is useless as it just redirects you to a page on bt.com that no longer exists).
  
• Tried the website and the "Message Now" button for online chat never appears.
  
• Tried to call, it just directs you to a conversation with a "BT Diagnostics bot" over text, and the bot wants to drop and reestablish my broadband line, which I don't need it to do.
  
  

Going to try to use words like "complain" and "human" to hopefully speak to a real person.