hello
i don't think boxes are black listed.
there is so many boxes bought on e-bay that were someone elses
the we had cards mated up no problem.
i had a box go bad,and ordered one on e-bay years ago and had a card mated to the used box i bought and it has been working ever since.
always good to have someone in the uk call sky.
give them all the information and box id number and say you bought it used if they ask.
if they don't ask don't tell them.
give all the card information and all they ask post code in the uk etc.
the now you should nhave the card mated to the card.
ralph