I have already tried switching off for second, for minutes, even for an hour or so. I have also tried the box on another HD TV.
Freesat seem to advise a Channel Re-set. Unfortunately I cannot find the manual I got with the box.
Done it - thank you! Now my wife can watch QVC!!!!!!
No further questions or advice required for now. Many thanks for your excellent (rated) response. QVC now reigns supreme in this house - for better or for worse!!