On my 2nd Freesat box in my study (a cheap Goodmans box) only some of the 24 channels have shown up... I get 3,6,9,12,13,16,19,22. These channels just showed up on their own. On our main Freesat (a Humax) all 24 showed up but that's an HD box and this one is SD. Any thoughts or advice please?