with co-op from the various CP's we have built up a database of adsl connections and their downstream attenuation. if the downstream attenuation changes for the worse by more than 6Db a fault is raised(with permission from the CP and EU) and tasked to an engineer to pair quality test the line to find where the loss has occured and restore the line back to the baseline figure from our database.
this should make reporting slight faults easier as all your CP has to do is compare it to the baseline and call us out.
usual causes are slight HR's and the blue beans.
if you've had a pstn fault and the engineer has changed the e-side(into a longer cable) then someone has to go back and put it back into the shorter one(so your speed is safe)(izools you'll have to wait till they poll all the lines again to get your baseline reset).