Hi @kkbn , welcome to the community!
The winter offer was for people who never had rpemium before, you should contact with Spotify Consumer Support filling this contact form, or tweeting to @SpotifyCares.
If you receive an automated email that leads you back to the community or help pages, reply to it (even if it's from "no-reply") and one of the Spotify team members will get back to you as soon as possible.
Don't forget to check your Spam Box 😉
Hey there you, Yeah, you! 😁 Welcome - we're glad you joined the Spotify Community! While you here, let's have a fun game…