Unable to redeem gift card

I purchased a laptop from Dell on November 26 and redeemed two gift cards for the purchase.  When the computer arrived it was not as specified so I returned it to Dell.  I was contacted after the return was received to notify me that the refund would be issued to my credit card.  I mentioned that I had used gift cards for a portion of the purchase.  I was then told the value would be restored  to the gift cards.  I told the representative that upon redemption of the gift cards I destroyed them and a new card would need to be issued.  That did not happen.

I have now been told by customer service multiple time that Dell is not responsible for lost or stolen gift cards.  I have explained the cards were not lost or stolen.  I redeemed them with Dell.  Still no success.  I have even offered to provide my third party purchase receipts and activation codes.  I have been told there were ways to fix this through Dell rewards, later to be told that would not work.  I find it hard to believe that Dell would try to take my funds, but maybe that is the case.  Can anyone help with a possible resolution?  It would be comforting to know that someone at Dell would actually listen and be able to solve this problem in a just manner.