Hi Gandalf2, thank you for returning to the thread to keep us updated!
I just want to check - are you able to get sound out of the soundbar from the TV360, its just that you are unable to control the volume level via the TV360 remote? Also, is the soundbar connected via HDMI-ARC?
You may find this thread helpful 👉 Solved: Re: Help with sound bar - Virgin Media Community - 5011776 where other community members discuss some of their soundbar connectivity issues. There's a particularly helpful post at the bottom of the thread that includes pictures of their setup and solution.
You may also want to check your Audio settings on the TV360 currently. You can do this via Home > Help and Settings > Settings > Network. (There are some further instructions here if needed 👉 How to change the settings on my Virgin Media box | Virgin Media Help).
Let us know how you get on and we will be here to offer further support. Thanks for your patience in the meantime! 🌞