I really don't know from your post exactly what you are trying to do.

If you want to extend network without running long cables then use Homeplugs - very efficient.
If you want to extend the phone line use RTX Phone Line extenders - again very efficient. Note: you cannot extend adsl phone line via the RJ11 extenders. But it will definitely do the Sky box.

Maybe some extension wiring has been damaged; check that all the extension points are connected correctly. Now with modern telephones, only two wires are required to be connected 2 & 5 (2 Blue with thin white bands and 5 White with thin Blue bands).

http://www.telephonesuk.co.uk/wiring_info.htm

http://www.wppltd.demon.co.uk/WPP/Wiring/UK_telephon...