Switch to BT. They have a Live Chat that actually allows you to speak to people and a call centre. They will give you a huge deal for 45 a month or less, with guaranteed max strength wifi. They will also give you 120 pounds reward for joining (at least they did for me).
you’ll want the SuperFibre Complete Wifi Package. Go talk to them on live chat. Bt.com - https://www.bt.com/broadband/complete-wifi/
I feel the same, just logging in to a device is impossible. Works on the web but not on the device seems to be really common on the forums yet no actual solutions. No one around to ask either. I'm with you I'm a 2 hour old customer and I'm already quitting and will be sharing my experience with friends and family to save them the heartache. Shocking product, Netflix and Amazon put sky in the shade now just need their content to build a bit more and they will be my go to media services.
I would recommend these....
I have the TP-LINK TL-WPA7510 WiFi Powerline Adapter Kit - Twin Pack, which I got for £49.99 when Curry’s had a special offer. Worth hunting around for a better price, which Curry’s will match.
There’s a cheaper option, but it’s slower, and more limited.
As long as the upper flat is on the same mains circuit as where the router is - that’s important - you can plug the non-WiFi unit in near the router, and link to it with a short Ethernet cable. Then you plug the WiFi unit in any mains socket in the top flat, and use the WiFi there.
In effect, the units use the mains cables as an Ethernet cable, so it does not care that WiFi from the NowTV router has difficulty passing through a folded sheet of paper, and your BT Extender won’t work.
A few general points...
I’m a customer like you. If you want Openreach back to your place, you have to get in touch with NowTV Broadband, on the number they gave you, which you should be able to find in My Account/Orders &appointments.
But do you want Openreach back? You have the connection to the property, and their responsibility stops there - internal wiring is the responsibility of the owner, and even if you have the router moved to the top flat, it then won’t cover the areas it covers now.
And re working over the internet; best not mention that. If you look at your NowTV contract, it’s quite probably prohibited.
And certainly, BT would point you towards their business service; rather more expensive, to guarantee you the extra continuity that busyness servers needed...