17 lost channels on my Samsung TV, channel groups C51 and C55

[Madelvic]

Tried to watch BBC4 HD last night and TV said the channel wasn't available.  It showed in the Guide.

Retuned the TV and now have lost all 17 channels in two Channel Groups.  Transmitter is Black Hill and groups C51 and C55 have gone and don't appear when I retune

I've retuned two Panasonic TVs sharing the same signal and they have the channels

Any ideas why the Samsung won't tune these groups?   Very frustrated here!   Thanks

[Madelvic]

Wow year later and not a single response.  TV seems to be ultra responsive (or not more like) to weak signals.   I've tweaked the aerial with a signal meter and replaced a defective aerial lead but still intermittent.   My 5 non-Samsung TVs work without issue.  Just not good enough Samsung