Walmart

I have a problem with getting a refund on a Walmart visa gift card that I purchased then immediately realized that it was the wrong kind of gift card so I went back to the customer service desk for help and was told that I can get my refund, but had to call the number on the card. The girl at customer service told me that I had to activate the card first so she opened it up and activated it for me then had me call the phone number. I've been shuffled to one department to another now for a week and now they're all saying that they can't help me although according to everyone I can get my money back. This is a $500 gift card and I'm furious that nobody will help me get my refund! Now they're saying they can't help because the zip code was not my zip code. I believe that the girl who activated my card for me stole my card when she activated it. I want my money back!