A crazy-looking graph.
As for a possible HR fault, it is difficult to say.
When you use the telephone, does the line seem noisy? Hisses? Buzzing? Crackles? or Pops? Have you tried making a call to your line whilst watching the
RouterStats graph in real-time? If so, does the noise margin "jump about"? Finally, has there been any change in your line attenuation?
I would employ a technique that
Black Sheep recommends. Connect a Time Domain Reflectometer to the incoming pair and adjust it so that a clear display is obtained which shows the presence of the MSAN / DSLAM. Then, from a mobile telephone, make a call to the line. If there is any change to the graph -- especially if the changes occur in synchronism with the "ringing" voltage applied to the line -- then that might indicate the site of a potential HR joint.