what can I do to get my gift cards funds back?

So recently for my birthday I was gifted a 50-dollar Xbox gift card from a sketchy CVS in Houston TX, I live in San Marcos TX. This CVS has had an incident previously where an employee stole the funds from gift cards they sold, however that was a while ago. I received this gift card in the mail unscratched and with the receipt to prove the purchase, but when I went to redeem the gift card I was given the prompt that the gift card had already been claimed somehow (I had just scratched the code). I went through Microsoft support to learn more and was told the gift card was redeemed while still in the mail, but they wouldn't tell me more such as who redeemed it or where they were. I tried to file a complaint with the escalation team and was told they would get back to me in 3-5 days, but it has been a week with no response. I want to know what I can do to get the funds from this gift card put back onto the card, it was a gift from my dear aunt, and I can't get the money back from the CVS because the gift card was redeemed after purchase and that doesn't qualify with their policy. Please help me

:)