I have a DV3 Box and for the last 5 - 6 weeks I have not been able to get?

I have a Sagem DV3 Box and for the last 5 weeks or more I have not been able to get BBC2 BBC 3 BBC24 NEWS, I have tried resetting it loads of times over a period of time, but it still will not put them on. I have a friend who has exactly the same box and has the same channels missing who lives on the other side of the town. I have always had them before, and so have they, do you know if there is anything I can do. I have another set top box off the same aerial and I get them all on that one. however it is a different make and a newer one, I had the channels when I installed that one so it is nothing to do with that.