Xbox Live Gold Promotion Issue

Hello there,

First time posting in the Microsoft community, but I was directed to post my issue on here after being transferred through multiple Microsoft online support teams/departments discussing my issue (for almost 2 hours over online chat and then phone). I purchased
an xbox live gold subscription during the buy 3 months get 3 months free promotion that ended on either Friday of June 15, or that very weekend. I saved that code until today since I used the free xbox live gold code that came with my console that ended yesterday.
However, my issue is when I redeemed that code today, it showed that my xbox live gold subscription ends on 3/5/2019 instead of 6/5/2019 (so, 3 months instead of 6 months). *code was purchased online through the Microsoft store

I first contacted Xbox and Apps chat who verified with the Promotions Team that my purchase order was legitimate since my order history did not show I got 3 months free (it only showed the digital code for 3 months that I purchased). They then directed me
to the Ask Experts online chat where I then talked with the supervisor by phone where I provided my case number, but then they transferred me to another person (did not catch the department/team name) to better assist me. He tried helping me by going through
my order history and asked if I received a free 3 months code on my xbox live messages (but my messages didn't show any xbox live gold codes).

So, that is what brings me here since he said the official members of this community could help me solve this issue so I can get the 3 months of free xbox live gold from the promotion that I was supposed to after redeeming the code today. I know it's only
$24.99 for 3 months and it happened a while ago in June, but I was hoping the promotion deal can still be honored?

:)