gift card refund issues

I need help with a gift card refund. I had a dell promotional gift card and bought a few items in Nov 2017 . I had to return one of the item as it had issues  . The promo card expired on 28 Dec. I had returned the item on Dec 2 . I waited but did not get the refund by Dec 28th 2017 . When I try to call customer care they said they cannot help to process the refund as the promo card has expired. But I did not get the refund in time so that I could use it to buy something else. It was not processed in the 3 to 7 days time frame.  They requested me to call sales and see if they could help me. They said they cannot help and transferred me to the gift card department.  They also said they cannot help with the issue. Not sure  what to do or which department to call for support. I feel this is not fair as dell did not process the refund in time .