Having had several interactions with VM support, and been told different things, and remaining very unhappy, here's my summary.
1. An engineer visited, faffed about for a while (including changing a bunch of settings on one of my handsets, for no apparent reason), contacted some colleagues but was unable to help.
2. I was told (via 150) that I had both voicemail and call-waiting, and that these are incompatible. I never asked for call-waiting. It seems to have been added when my line was switched to digital.
WHY DO VM PUT INCOMPATIBLE FEATURES ONTO ANYONE'S LINE?
3. I was told that it was necessary to remove both features and then re-enable voicemail. But when I got through to customer support (who weren't available during the weekend), they said that it was only necessary to remove the call-waiting; which they did.
IT IS NO BETTER NOW.
What I think is happening is that there is no FUNCTIONAL problem; i.e. messages arrive, the dial tone changes, a message can be listened to, and the dial tone changes back.
BUT IT TAKES HOURS AND HOURS.
I left myself a voicemail and it took at least TWENTY HOURS for it to be signalled by the dial tone. After I listened to it and deleted it, it took another FOUR HOURS for the dial tone to change back.
What use is a voicemail system that takes this long to react?
The analogue system didn't have this problem. HOW HAVE VM MADE THEIR DIGITAL SYSTEM SLOWER THAN THE OLD ANALOGUE ONE? Not just slower, but massively, unusably slower.
This looks like a case of something that's free being worth every penny (and no more!).
Except that it isn't really free, is it. It's just included in the price without the option to do without and not to pay for it.
By the way, this page: https://www.virginmedia.com/help/landline/managing-your-landline-calling-features
(and note that it specifies "landline") has a link labelled as "Find out how to set up landline voicemail here." (Note again that it says "landline".) But the URL is https://www.virginmedia.com/help/mobile/set-up-virgin-mobile-voicemail, which (as the URL indicates) leads to a page about MOBILE voicemail. Honestly, I despair!