my sagem freeview box won't change channels?

i really am not sure whether it's the box itself or if it's the remote but my sagem freeview box is stuck on one of the children's channels (CITV) and will not shift. i have put new batteries in the remote but no joy. when i switch the unit off and then switch it on again, the same channel just appears on the screen. i cannot get the volume to come on either. the more i think about it, it definitely sounds like the remote to me. what do you all think? has anyone else had this problem? please tell me it can be fixed. fingers crossed. thanks in advance as any replies would be greatly appreciated.