freeview transmitters -uhf band?

I have an ex ondigital box which I have reinstalled new BBC channels.
I was tuned into east mids waltham transmitter, but now i am picking a signal from ? as I get northern and Lincolnshire news, I live in Warks.
I have spoken to the Beeb andthey said I should not be able to receive in my area.
I can but I occasionally get pixalations.
When I check the signal strength it shows nothing on a HF band 21,
Any suggestions

Alan

 

off the top of my head try HF channel 38, to see if you get more signal strength
This worked for my old On Diggy box in Scotland and also for a friend in Birmingham.