Bad GA creator i think

If you won the GA 3 days ago, he's still got 4 days to send it. Doesn't sound likely that he will from what you've said, but they have a full week to send the game.

Just wait until 7 days have passed and mark not received

But why he blacklisted me?

If you can't find any info, it means you have been rerolled.

Maybe you didn't meet the requirements/ rules he stated on the page of the giveaway, or it was a pack/bundle and you owned some part of it (exemple : giveaway was a GOTY game but you already owned the base game).

How would you know if he blacklisted you ? He can't do it once you've already entered. If you know you won, it means you weren't blacklisted.

The reroll seems more likely.

edit : what giveaway was it ?

everyone has reason.
Mark as not received and move on.
if he doesn't give support a good reason for a re-roll (he won't probably) he will lost one slot of the GA's he can do.

You'll win more.

You can contact support and provide a link to the giveaway to ask if there is any information on what happened, however it's only been 3 days so I would suggest waiting a few more.

Closing this, just in case, since I noticed people have asked for the giveaway and you should not point it out on the forum.