The most likely reason that you have poor BBC pictures is that your 9300T is not tuned to channels from just one of the broadcasting transmitters. What you are seeing is probably a weaker broadcast from a different transmitter for where you live. The duplicated stronger channels will usually be further down the TV list and guide.
This issue, and other issues that accompany it on a Humax, can be cured by clearing the current tuned channels and retuning manually.
One method of manually tuning to receive the strongest channels and get rid of other potential issues is explained at the following link http://forums.digitalspy.co.uk/showpost.php?p=57505565&postcount=4
See also
https://myhumax.org/forum/topic/channels-go-scrambled-in-the-evenings
http://forums.digitalspy.co.uk/showthread.php?t=1157236
http://www.wirefresh.com/humax-promises-fix-for-pvr-9150t-pvr-9300t-and-pvr-9200t-pvr-issues/comment-page-2/
http://www.howtomendit.com/answers.php?id=143376
https://www.avforums.com/threads/humax-9150t-problem.898290/
Next time try this: http://bit.ly/20zFzIh, April 2016