aww poor UB
Seriously though... whilst adsl2+ can improve speeds on a lot of lines.. the general consensus is that for the longer lines it can sometimes make things worse.
Therefore some of the more "cautious" ISPs will reject the order rather than putting you on something where you may end up an unhappy bunny. Hence also, why the likes of UKO will accept orders but leave you on the same IPStream product.
IMHO this is far better than the dubious tactic of promising speeds that arent really available due to the physical condition of the line. There is perhaps one ISP that I can think of whose LLU service
may benefit you, due to their lack of the BTw IPprofile system.. but Im not sure if I rate their actual service and speeds.