Been there done that, my line is 3.9km and subject to unpredictable noise
spikes.
As others said, there is nothing YOU or an ISP can do about the line, and BT
/ Openreach probably won't.
On the other hand the ADSL checker is often unduly pessimistic.
I would suggest that you go with
www.plus.net:
a. go for the cheapest £9.99 option 1 to start with, you don want to pay a
lot for what might be 250kbps.
b. they are very good on customer service, via their website or ordinary
phone line.
c. while they are independently run, they are owned by BT, and know how to
get BT to do their job.
While ADSL2 will be of no help on any line with more then 49dB attenuation
(mine is 51dB),
some ADSL2+ capable routers work better on long / bad lines.
After trying different routers I found that BT1801HG (made in US by 2Wire)
works lot better on my line then other expensive routers (and has got a
great WiFi too). You can find one,or the later BT2700HG, on eBay at very
good prices.
Regards,
Martin
PS If you do go with PlusNet please use my ID 'wester' as a referrer and
save me few pence, thanks.