"To Return an Item to a Store
Take the item, invoice and all original packaging and accessories to Customer Service at your local Wal-Mart.
For all payment methods except Bill Me Later®, an associate will issue an immediate credit to the original payment method or provide a store credit for the cost of the item and the sales tax, if applicable.
For an item paid for with Bill Me Later, an associate can issue store credit in the form of a Wal-Mart Shopping Card or a cash refund. Then you receive a bill from Bill Me Later and submit payment to Bill Me Later."
http://www.walmart.com/catalog/catalog.gsp?cat=120564#0