Yes it can, but the Ofcom requirements and Openreach implementation are supposed largely to prevent this.
Who to contact about it I don't know. Basically the ISP(s) of the people affected. It is possible there is something wrong inside either the FTTC or PCP cabinet, or an incorrect setup. (Wild theory
I suggest that if there are a number of people on any particular ISP affected that somehow a joint problem report is raised. That might trigger more than a few individual ones would.
The indispensable man or woman passes from the scene, and what happens next is more or less the same thing as was happening before.
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