That's terrible.
To re-cap, the line was working perfectly well (Dial tone) right up until the actual 'Managed Install' took place ?? It's either co-incidental that the D-side cable has developed a fault at that exact same time, or something has gone wrong whilst connecting up in the Cab ??
It's all guess work as I can only go off what you say, and I'm assuming you're getting it second-hand from the EU ?? There may well be a definitive UG issue, but I have to say that irony is playing a helluva hand if what the EU has said is the complete story ??