I'm not sure how useful that map is.
The highest number of reports are where a lot of people live.
It does look as though London, for example, it getting hit worse than Birmingham, but none of use know enough about the Plusnet network to know what's different. In the past, I've often been told I am somewhere close to Milton Keynes, presumably because of the IP address, but the helpdesk staff seem to be based in Sheffield.
In the past, with other companies, I've known that a particular cluster of equipment had failed, but I wouldn't like to guess where my connection goes physically. The connection is working for me, but if it wasn't I doubt the red spot would show on that map.
Milton Keynes, incidentally, is legendary for having something falling down on it. There's a song.