three month groove music pass did not work at all

Contact official support and let them check if the code is valid.

If valid, they will assist you in redeeming it.

If invalid, you'll have to contact your reseller.

contact support here: support.xbox.com/contact-us

Hi there.

Please log in to HERE and check to see if there is a Past Due on your account. If there is, it will be highlighted in RED text.

Past Due amounts must be paid in full before you can redeem codes successfully.

If there is no past due amount, you can try redeeming the code on
Xbox.com.

If that does not work, then you should get in touch with Xbox Support Chat so they can have a look at your account.

Regards

I signed up on August 14th 2016 for groove music pass during the 1 month +3 months free and did not receive my code for my extra 3 months free. Could I still get it?

I responded to an email from Microsoft on 7/13/2016, signed up for a 30 day Groove Music Pass subscription on the promise by Microsoft for a 90 day Groove Music Pass access. A promo code has never been received. I was passed from one chat support representative
to another to another to another and then after spending 30 minutes was sent here. Maybe this will get resolved soon.

Their email stated "Rev up your summer soundtrack with 3 free months (90 days) of music.* Just sign up for Groove Music Pass, and after your first paid month ($9.99), we'll email you a promo code for your bonus months (as always, you can cancel anytime).
But hurry - this deal won't last forever."

The music groove promotion was only available for first time user here is a link to check to see if it is the same promotion that you had.

*Offer valid until 12:00 AM GMT July 1, 2017 or while supplies last. Codes for additional free months must be redeemed by August 15, 2017. Customer must sign up for a free trial (new customers only). Credit card required. Prior Zune, Xbox or Groove Music Pass
trial customers not eligible for free trial. Free trial continues to automatic paid subscription unless cancelled. During the first 30 days, customer will receive a token for 3 months of Groove Music Pass at no charge. Tokens will be delivered to subscriber
via email or Xbox message center
https://www.microsoft.com/en-us/groove/evergreenplusthree.aspx?crm=groove