Why does the red button function not work?

My Humax PVR 9200T 'freezes' but am hoping to sort it out using advice on the site but having retuned it this week the red button function does not work with BBC channels. With retuning the BBC channels have moved from 1 and 2 to 800, 01,02,03. ITV and channel 4 remains on 3 and 4. This change alone has been frustrating but can anyone help me with the red button failure?? We pick up from the Mendip transmitter in the SW.
Thanks