Microsoft not fulfilling an advertised promotion price. Who do I contact?

So I turned on my xbox today after being completely off and signed in. I do this to make sure any news/offers/promotions are freshly updated. When it finished starting up I saw the offer for 50% off 6 months of xbox live gold and xbox game pass. Clicking
the tile directs me to the xbox gold page where I can purchase it at the advertised price and under that is a tile for the game pass promotion. None of the ads say anything about restrictions or limited availability, but the xbox gold is available and the
game pass is not. I can also see a tile in the game pass tab of the dashboard with the same offer.

The offer is displayed in multiple places, and half of the offer (the gold) is available. Text and phone support both told me "There is nothing we can do" and refused to refer me to somebody that has the authority to do anything.

I'm not paying full price for a 12 month subscription, and am not interested in a monthly recurring subscription with microsoft after they tried to hold my account hostage after i had cancelled my subscription and they mistakenly continued to provide service
for months afterwards.

What are my options?

:)