The second upstream just reappeared.
It's been a long period of the same problem, dating back beyond 23rd September when I started a thread about it on their forums.
http://community.virginmedia.com/t5/...up/m-p/2917052
It's not every day, but about 3 or 4 times a week. I've been posting them the relevant info as it appeared.
Long periods between responses from VM though. Moved to SHUB 2ac, new PSU, multiple checks... same fault.
Time to take it higher as you suggest.