While I've got my install booked for next Wednesday afternoon, I did try following up afterwards to see if I could upgrade to VIP50 (currently on VIP20) - so that the broadband side of things could be done on the same afternoon (ie: superhub install).
Unfortunately they weren't able to attach to the current work order(?), and they would have had to cancel the current TiVo install and re-book everything - which was a bit of a pain, as I'd already booked the afternoon off. Their suggestion was to phone up and sort VIP50 out once TiVo was up and running.
So the moral of this story is to decide whether you want to upgrade to VIP50
before phoning for your TiVo install.. not after!