There are a lot of channels which are going through frequency changes due to the roll out \ expansion for the 4G mobile phone signal which appears to be causing some interference.
The best thing to do is perform a factory reset, followed by a re-tune.
Instructions for tuning can be found page the bottom right of page 20 here, and instructions for a factory reset can be found at the top right of page 73.
In essence go to Setup, General Settings, then Reset All, and when prompted select Yes to the confirmation
To retune go to Setup, General Settings, Channel, then Auto Tune
If this doesnt work (channels are not in the correct order), you can follow the manual DVB tuning instructions on page 22 of the same manual, which allows you to reorder them, however a reset and re-tune should allow the TV to resort the channel order for you.
Please let me know if you need anything clarified.
This sounds like a failure on the control board, a new board would be around £100, plus labour.
If you would like me to recommend a repair centre for you take it in and have the board replaced, please provide your postcode.
Ive check to see if there are any new firmware updates, and nothing has been released in the last 6 months so I dont think there is a known fault, which a firmware upgrade would fix.
I would recommend Burdens (160 County Rd, Swindon, SN1 2DY) unfortunately they arent picking up, but would if you pop down with the recorder they should be able to give you a estimate. Their number is ***** 485454.
They are very good, and have had numerous customers come back with very positive reviews, failing that you can try Genserve on 01793 886333, they are rather pricy, you looking at around £80 in labour repair charges - at which point its cheaper to buy a new unit.