Dude that is a specific line problem, only with you.
Today I am synced at 2047/511 after a long long time.
I am no longer hearing Cross talk on my normal telephone,so the cross connection in my line is rectified.And My SNR stats are back up so I enjoyed full speed last 2 nights
If you want your problem resolved,go meet the Triband Head at second floor and tell him how your SNR/Attenuation stats fluctuate.
He will try and brush you away saying Complain to 1500/1504,give application,problem with internal house wiring or something else.
Tell him to tell his linesman to get u a fresh line