I am a solicitor in the West o Scotland. I will try to help you with this. How long have the wires been there? What is the planning matter you can't move forward on. What do your title deeds say about the wires, if anything? Have you asked them for a breakdown of the £40000. In passing I would comment that I lived I a rural property myself and had the same problem. BT transferred the cables underground in a day and the cost was a few hundred pounds to dig a channel put in a pipe and reroute.
Do the title deed provide for passage for cable and wires?