Where I live, in France, I use Orange for my Internet/TV/landline connection needs. Orange owns the backbone and everything up to my house. If I have a problem, there is no finger-pointing to be done, it's all Orange's responsibility from start to finish.
That is why I have no intention of leaving Orange for SFR, as SFR regularly asks me to.
If I did that, then I would be right smack in the middle of the same problem you had, SFR saying that it's Orange's fault and Orange saying the reverse.
I've been there before, I have no intention of going there again.