Did you every get a solution to this?
I have the same problem. Moving my ADSL to BT halved my upload speed.
With my last ISP I was on the old style 20:1 ratio IPStream product that had 832Kbs upload. Now I have moved to BT but they cant offer me the same, its just not an option on the system. I have spent hours on the phone to very helpful staff but most of the time they just dont understand the fact that its just a different product.
Is there really no current eqivelent of IPStream Max for people stuck on the 20CN?