Fascinating read for the intelligent non-specialist! I hope I qualify for this description.
In respect of my REIN fault, Openreach were back on site yesterday to investigate the particular premises that was identified before the weekend. I was not involved initially, but Openreach reported afterwards that they had located the source of the REIN. It was the power supply for a Belkin USB hub. Once this was taken out of use my SNR margin improved by about 2 dB.
However my problems were intermittent not continuous, and the SNR drop could be 10 dB. Clearly Openreach found a fault, but I don't think it is the fault that is doing the serious damage! Time will tell.
After Openreach departed I spoke to my neighbour and we did some 'testing' of the faulty unit. We plugged it in, in my house, and used my radio on 612 kHz. There was clear interference but the sound was entirely different to the recording I made previously and linked to above in this thread. The volume also appeared to be much lower, but this could just be a different setting on the volume control on my radio. When I checked my Routerstats traces, I had lost 2 dB of SNR during the test.
I also looked back and saw the effect of the Openreach testing in my neighbours house earlier in the day. Temporary 2 dB gain when they switched off at the consumer unit followed by a permanent 2 dB gain when the offending item was taken out of use.
So a small step in the right direction but I await the next serious outage and further 'fun and games'!