Hmmm.
My local Co-op is displaying a notice stating that they're limiting their acceptance of coupons because of the large number of fraudulent coupons which perfectly law-abiding people are downloading from the internet.
At the same time Hot UK Deals has removed the £9 voucher offer from their site because (quote) "The HUKD community has flagged this deal as reeking of spam, therefore the deal has been incinerated".
http://www.hotukdeals.com/deals/sky-tv-50-off-twelve-month-packages-1627384
So I'm forced to wonder whether you've been conned, resulting in you purchasing a valueless voucher from a fraudster.
The only way to find out is to ask Sky by calling 08442 411 653.
Chris