Well, there's no entry for any Logitech devices in the default list here, but using the "search" function described here (under the "Control your AV device using your Virgin TV remote" section) may find a setting that works.
As a Very Insightful Person, I'm here to share my knowledge. I don't work for Virgin Media.
Thank you! Using the scan feature does find the PERFECT code, volume up, down and mute all work as expected, and sounds perfect with Virgin 🙂 It's a shame theres no way of me to find the code to type out as it took a while on scan mode.