We have a Beam setup for the TV. 

We bought a Sonos One (let's call this One A) also for the same room to create a ‘room’ but the One kept dropping off the network. I found a way of joining the two for listening to music but not really surround sound. We then found out to create stereo properly you need two of the same device. 

We bought another Sonos One (this is One and have successfully connected Sonos One B to the app and system but now One A won’t connect at all. I’ve reset it and gone through the setup and it comes to a screen on my phone that says it's added but may not feature in the system so should unplug and replug it in, but it doesn’t appear after that either.

What should we do?