I know this was a ling time ago but thought I would post the outcome of this over a year on lol

Basically this might be evident to a lot of people by now I havent researched this since 2012, many users might know but since changing my router yesterday my upload speed works way over 9mb/s and is maxing out its 20000 IP profile

It turns out the BT Homehub was to blame not the line, and ive noticed a post on the official BT forums where other users have the same problem and using as many as 4-5 hard resets on the homehub has jump started the hub to upload faster.

Changing my hub means im uploading near 18mb/s now