Update.
I managed to get an admission on the helpline that the pre-install date always becomes "tomorrow" on the system and they have no visibility from the third party contractor as to their plans.
The agent left a note on my account regarding the placement of the box and requesting that they did the work whilst I was home.
Yesterday I go a text asking if I was available in the afternoon, contractors arrived, pulled the cable and I now have a box on my wall exactly where I wanted it.
Main installation is in 14 days but I think I'll call and see if it can be brought forward.
