It looks I am not the first victim.
I ordered one month subscription, see detail information below.
Reward: Skype Unlimited US & Canada – 1 Month Subscription Order Confirmation: 520384455074010
and I got Skype Unlimited Voucher by the email,
But I could not redeem it.
In “Redeem Skype voucher or card” page it shows: Unknown error occurred. Please try again later.
Then when I tried again, it shows: You have tried too many invalid voucher or prepaid card numbers in a row. Please wait for 30 minutes and then try again. We’re sorry for the inconvenience.
I sent out email depends on the “contact us” link, but no response yet.
So it’s kind of cheating game, either Bing, or Skype.
Hope you will not trap into this cheating game!
3 days later, after I contacted with Skype team and Bing team, I got their apology, refund my credit and they also removed this voucher from the list. Here I also want to say sorry if I was using any bad words in this event.