At least you reached someone who can interpret the graph, or even if they could, are even allowed to and able to (and willing to) forward the issue upstream.

Usually ISPs here optimize for lowest possible maintenance cost (right away), which means leaving things in a degraded state forever, and fix it when it finally breaks (which can cost more than fixing it right away).

So in general nobody wants to do a costly fix for one user in a small semi-rural area, especially if nobody else complains (and they don't, they don't know or suffer through it, or have a 10 Mbps package anyway so they don't notice anything unusual).