You'll find the revised prices here:
http://www.whycable.co.uk/pricechang...Price_List.pdf
although it doesn't mention the £75 fee.
If you
change an existing STB to V+ - then there is a £75 installation fee.
If you
add an additional STB and have the V+ box - the £75 is not chargeable.
If you have an existing STB, and change one STB to V+, keeping the additional box, there's no £75 fee.
The additional STB fee is £5 if you have a V+ box
That's my understanding - someone will correct me if wrong.