Wifi calling keeps stopping - Galaxy S9+

[Robatwork]

I have a business pay monthly account with wifi calling enabled, and a Samsung Galaxy S9+ (all from O2 directly).   Very often the wifi calling simply packs up and I won't know until I realise I've missed a call after a reboot, or I see the wifi calling icon isn't on my phone.

When this happens I can't restart Wifi calling - the icon (highlighted below) in settings just isn't there, and the only way to get it back is to restart the phone.

I had a phone call with an O2 expert a couple of months ago about this, and they sent a new SIM card. Same thing with the new card though.

Any way to make this service more reliable?

[pgn]

WiFi calling can be funny that way.

Have you got the latest updates on your phone, @Robatwork - in case it is something that has been fixed since you started to use it.

[Robatwork]

I always keep my phone updated as and when it asks me. It's a shame I live in a black hole of reception where the villagers are anti phone masts so all networks are awful and O2 is the best of a bad bunch. This is in the London outer suburbs inside the M25 so not exactly the middle of nowhere.   I may have to do that scheduled phone reboot thing that I hate - the nice thing about being based on Unix (imho) was not having the laughable rebooting necessary for Windows.