After a lengthy (rather heated) discussion, Wal-Mart is NOT honoring these. Manager said "No way, no how." Then I called corporate and they said the same thing. A notice had been sent to all Site to Store locations that they would not be honored. I said they had already "reserved" the money in my bank account. Didn't matter at all. They said to expect a refund shortly. About 10 minutes later the money was back in my account.
If you haven't already picked them up, look for your refund emails shortly.