Attenuation

[#1]

Ahhhh, i see. Well, that will probably be it then.
Plusnet still think there is a faut, so guess an engineer visit is in order

[#2]

Images of box in question attached. I thought I'd ask again as there are three phone lines coming off this having looked at it; my own, and my neighbours.
Is it just a junction box, or something else?
Image 001 - The box in question. The cable coming in from the top-left is the main house-to-pole line, and the one disappearing at the bottom-left is my own line.
Image 002 - Better quality image showing all four cables
Image006 - The two lines belonging to my neighbours
Thanks
Will

[#3]

That's a standard BT66B style connector box. Nothing inside it except a number of reliable "jelly crimped" connectors joining the wires from each of your own connections to the cable going to the pole.