constant broadband outages in the early days (solved by bumping SNR up to 12 and reducing the speed to 3mb or less)
Does indicate a line issue rather than an ISP issue. Perhaps the Sky Hub / BT HomeHub were better at dealing with an underlying issue. Everything stated here, regarding the speed is pointing at the line.
That said, I doubt talktalk will send out an engineer if it stables off at a 12db noise margin - other ISPs would be more willing.
Seeing line stats would be useful. Line attenuation, sync, and noise margin.
EDIT: a 12db noise margin will slow the speed down, so this is why it's slower. A 12db noise margin should only be applied to a very unstable line (ie line fault).
Edited by ukhardy07 (Sun 03-Jan-16 10:59:00)