It's exactly the same for me, I have bought several 3900X and graphics cards which are advertised with this promotion.
The customer service is beneath all ***. Then I'll just go to the competition if Digitec no longer values its customers.

Just write to the support. I didn't get my code automatically either. You'll get one sent to you. Digitec doesn't seem to have got the hang of automatic dispatch yet :P

The game offer was probably added later

Answer from support: To my regret, I have to inform you that we as a retailer are unfortunately not participating in this promotion and for this reason a game code is not included with an order. I hope for your understanding.

It is better to buy from a reputable shop that is also allowed to participate in such promotions.