If your gift cards show as “already redeemed” but the balance is not in your account, this requires Microsoft Support to check the redemption and billing history on your account directly. Community/forum users cannot access or verify account-level transactions.
Please contact Microsoft Support here: Contact Support. Sign in, choose Billing & purchases → Microsoft Store, and request chat so they can investigate and restore the balance or correct the charge.
Have your receipt, gift card codes, and order details ready for faster assistance.
Hope you'll get this sorted out!