Yeah it did smell of buck passing to me, but TBH now I've got my old downstream rate back, I'm happy to leave things as they are, and draw a line under the topic for now..
However, 3 things have become clear to me since I started this thread:
1) You guys - Kitz, Astral, Roseway, Mr Chris, Rizla and everyone else who has helped along the way are truly great guys (and girls).
2) Tiscali don't know their SNR from their attenuation.
3) I'm a little bit older, quite a bit more wiser, and a lot more cynical.
Once again, thanks to all of you for putting up with me.