Yes, indeed, UKTVG2+1 is among that happy bunch of bad channels. I hadn't noticed before as it only comes on in the evening

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I really appreciate the help on this one. I totally agree with the principal of reporting the fault straight away and then making sure it is handled properly. I used to work in an office-based job at BT where we analysed the performance of the PSTN repair service. I have a vague knowledge of the way telephone cable used to be run and some of the terminology, but of course CableTV is very different.
Indulge my curiosity if you will;
My STB is connected by co-ax cable to a box on the wall (installed some years before I moved into this house, it says "Cable & Wireless" on it). This is the junction to a cable (co-ax copper?) that goes out to that footplate cover... which contains another junction?... which goes to a cabinet up the road which takes all the feeds from my street and condenses them down onto a fibre cable that runs to the nearest Exchange building?
Does that sound right? Maybe a little bit?
I'm just thinking that if I knock on some doors of neighbours that have Cable TV I might find others that share my problem and I can get them to report it at the same time as me... oh, alright, maybe that is stretching it a bit!
My dodgy reception on those channels has been constant and was first noticed soon after the install which happened on 29th March. Is it a coincidence that all these unwatched channels are on the same frequency?
If I was to assume that the cable was breaking down (water ingress, damage, etc), would I expect eventually to lose other channels, in a bunch? What would be the next frequency range to suffer (and which channels)?