Walmart Super store gift card bought at Walmart American express was a scam , Never properly loaded and never activated $500 Belleville Illinois

My son bought at Walmart a prepaid American express  gift  card in 11/17/ 2015 for the amount of $500 with the fee of $4.46  all paid cash. When he went back to walmart store was shock to know that there was 0 balance on card.  He called the manager to report . The manager at that store said Walmart has nothing to do with the Amercian express card. The American express card check the card and said the card was never properly activated and loaded at the time of purchased . Then the manager fax all the receipts and information to the American express Prepaid Resolution Team  and the reply was  they are requesting more ducoments and that the receipt did not match.  It went on and on sending more documents. Nothing was resolve. We made a lot of phone calls to the Walmart costumer sevice they keep saying we are working to resolve the issue. The manager of Walmart in Belleville was contacted and now she is saying the card was loaded . How does she know? So many phone calls we made to Walmart and they seems to avoid resolving this issue. It is not the first time this happen I read in your ripped off website about Walmart gift cards that this happen to other costumers too.Is anybody listening of Walmart people? I hope there is a law suit  filed in this issue because it is so unfair. Please somebody help.