Dollar General

On 4/6/21 I bought 6 Amazon gift cards, when I tried to use them 1 showed as invalid. I contacted Amazon and they said that the point of purchase was responsible for a refund. When I went back to the store the manager told me that Dollar General was not responsible for the card. I want my money back on the invalid card. Store number is #03393. Amount of gift card is $100.00. My name is Terry Cooper 24 Wilczek Rd. Lumberton, Ms.