How can I get a refund for $500 in invalid Apple Gift Card I purchased?

i bought 500 of apple giftcards from my local superstore i wernt they say with recipet and gift card that had said activated and when i went into the store told what happened they said they can't do nothing about it i sisi not get refund my money back i had proof all i was told beware of scam of told it actived being told it not working yesterday in the store int the with one customer service went through how many moved self check before finally let my payment go through went i exxperince my 500 in value cards they would not remeburse me what am i suppose to do im out 500 dollars how do i get my money back embused the store sold used apple card what can i do

[Re-Titled by Moderator]