Problem with my Grundig Sky Digibox!!! Help??

For a while now my Grundig Sky digibox that we got in i think 1998-99 gets frozen on channels, we still receive an image and can watch television, the box is still receiving the command from the control however it freezes and we cannot turn it off via remote or change channel or anything, the way we resolve this is by turning it off by the mains however this is getting pretty tiring and tedious now.

So any info or help will be much appreciated.

Thanks