I bought an Apple Gift Card, but the card keeps showing it has been used

Please follow the steps in this Apple Support article. 

If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card - Apple Support

If after reviewing the article, and following the directions in the article, you need additional assistance please follow the link below to contact official Apple Support. 

Contact Apple Gift Card Support

If you receive a request for payment using Apple Cash, or If you believe you are the victim of a scam, please contact Apple Support and report it to local law enforcement.

You may also report the scam to the FTC Complaint Assistant.

Please don't back a Gift Card at a retail location that displays Gift Cards on racks where they can be easily tampered with. The retailer is not protecting your purchase. People will peel off the sticker and write the code down, then replace it with another sticker that can be purchased from Amazon. They will wait for you to activate it, then spend the balance before you get a chance too. Only buy Gift Cards where they are secured behind a counter or directly from Apple. It is a common scam that retailers know about, but some don't seem to care if their customers lose money.