Just as a follow-up on this - over three months since the order was made, we're still waiting for our install. I had almost given up on it, but yesterday the weekly "we're chasing our contractor for an update on the civil works" update email changed to saying the works are due to be completed on the 3rd February.
And indeed, on checking the scheduled roadworks, there is Virgin Media work scheduled outside our office for the 2nd-4th February with the description "DL, CLEAR BLOCKED TEE IN FOOTWAY AND LIFTING CARRIAGEWAY PIT LID".
So who knows, maybe the install will complete this side of Easter.