Forget broadband and concentrate on the telephone side of things.
Unplug BB cable and try the quiet noise test with a corded phone in the test socket (remove covering faceplate).
If there is any crackling (noise) then inform the company that you pay your telephone bill that there is noise on the line.
Was Eclipse Home Option 1, VM 2Mb & O2 Standard
Now Utility Warehouse (up to 16mbps) via Talk Talk