What should I do?

Request a reroll.

Technically you have 7 days to get it to them. Try commenting on one of their old giveaways and let them know that you have attempted to give them their win on Steam. If you still get ignored, then it is possible you may have been blacklisted on SG as well. After that, then open a ticket and request for a reroll. At least the mods can trace where you did attempt to reach out to the winner.

Make a screenshot of you trying to send them a friend request on Steam, wait 7 days, request a new winner.

I think you got problem, because steam discount on specific game will last for 5 days more only?

a flaming bag of dog poop always works for me.

this is so annoying... I got reported for commenting on the winner's profile as well, and received a 2-day community ban and a weeklong cooldown from buying games or community market items too...

If they're deliberately preventing you from making contact and delivering the game, I'd take screenshots and include them in a redraw request even before the 7 days are over. If the evidence is clear enough, I'd like to think that mods would accept it rather than forcing you to wait several days

I made support ticket with screen of winner steam profile where i don't have button to send friend request.
NOW I have to wait for their reply