Fracturing image periodically on some channels

[lithoartist]

I have a Sony Bravia TV, model 32W705.  It has suffered fracturing on some channels in the past or gives a "No signal" message.  It was Freeview Drama channel most recently.  I conclude it occurs when we experience poor weather.  It led me to wonder whether it might be the transmitter chosen: I had selected "Berkshire and Hampshire", I believe, instead of London so that I might obtain automatically BBC South.  I am unable to find the process I used previously to select or change a Region, however.  I guess it was in Settings/System Settings/Auto Start-up or Settings/Digital Set-up/Digital Auto Tuning but nothing has presented itself during the processes.

[lithoartist]

I have discovered how to select or change a Region, at least: "Continue" appears adjacent to the "Enter" button at the lower left of the screen once Auto Tuning is completed, which I had overlooked previously.  I remain mystified, however: Region 1 was displayed as "England", Region 2 as "London" and Region 3 as "Greater London", which surprised me.  I believed I had set Region 2 as "Berkshire and Hampshire" and Region 3 as "Reading" previously.  It suggests the regions return to a default following a rerun of Auto Tuning.  I returned to the TV and selected Drama Channel 20 to find a perefect picture, whereas there was no signal immediately beforehand!