Hey Chris
As fas as I'm aware, your attenuation shouldn't really be that much for that length of line.
I'm referring back to one of your previous posts where you said:
"i got about 4 ADSL filters in my house connected and only 2 phones are connected to 2 filters if i even remove a filter without a phone conencted my SNR still goes down by about 5db"
Would it be possible for you to draw a diagram of how all your phone wiring and where all the phone sockets in the house are... and where your phones, modem and sky box etc are?
I know it's a bit of a pain in the ass to ask you to do that, but I'm not sure your filters are all correct. This would help with stability. You can post the diagram up on something like
http://www.imageshack.us and link to it from here (using "forum code 2").
By the way, did you get the 1Mb regrade off Karoo yet?