Won a contest, and now the Xbox twitter account is ignoring me.

I was DM'ed by the official Xbox Twitter account that I had one a contest to receive a free Design Lab controller. I was told that I would have 48 hours to respond to the message, or my prize would be given to someone else. I responded within a half hour
of receiving the message.

That was 48 hours ago, and since then I have yet to hear back from them. They have seemingly ignored my messages, as well as my tweets at them. I dont know what to do at this point.

:)