Haven't got my 6 months of "Spotify Premium"

Have you checked your junk or spam email, it may have been put in there. If you have, and you have not got it, sometimes delays happen, so you might get your code in the next few days. If you do not, then contact Xbox support or Spotify support for assistance.

If you have ever in the past been one of the following things, you are not eligible for the Spotify bonus:

1. A previous Game Pass Ultimate member
2. A Game Pass PC Beta Member
3. A Spotify Premium User (even just on a trial)

I've found that a lot of people who post about this topic end up falling in one of those three categories.

I suggest you contact Spotify support https://support.spotify.com/

I never received the Spotify code

I was told by Microsoft they ran out of codes

BS

Hi AshenV4771,

I'm going to copy and paste the exact terms and conditions for this offer found on the Xbox Game Pass web page https://www.xbox.com/en-US/xbox-game-pass

• *Limited time offer valid, only in USA and UK, while supplies last. May take up to 10-business days for new members to receive Spotify Premium code via Xbox Message Center. Not valid for existing or previous Xbox Game Pass Ultimate or PC (beta) members,
  other exclusions apply. Limit 1 offer per account. Codes will be delivered through email before 3/20/2020. Offer cannot be combined with any other offer. After promotional period, subscription continues to be charged at the then-current regular price (subject
  to change), unless cancelled. Plus applicable taxes. Credit card required. Game catalog varies over time. Spotify disclaimer: $9.99/month after trial. Codes available while supplies last. Open only to users who haven't already tried Premium. Offer ends 4/1/2020,
  codes must be redeemed by 10/1/2020. Terms and conditions apply. Please visit https://www.spotify.com/us/legal/Spotify-6m-Xbox-offer for more details.
  
• **Sign in for your available offers. Offers are for a limited time and may not be valid for all members. Not valid in Quebec and Russia; other geographic restrictions
  may apply. After promotional period, subscription continues to be charged at the then-current regular price (subject to change), unless cancelled. Plus applicable taxes.
  

If you do not get the code via Xbox Live messages within 10 days then you will receive it by email sometime before 3/20/20. You can read up on more about this offer from the following FAQ: Spotify
and Xbox Game Pass FAQ

Basically all you can do is wait at this point for the code.