Same thing happened to me as well. I ordered Fitbit (even though i had the same offer in other sites I ordered in walmart cos i was ordering other stuffs as well) and other items like PenDrives HardDisk.
They cancelled the Items one by one (not all on the same day but 1-2 days apart about 2 days after i placed the order) saying the Item is not available. Lucky for me i had other similar options still available. They could have at least kept the order for future inventory(or pick from a different store) rather than cancelling it. Had to search for similar offers and place the order.
Hated the experience shopping in walmart online. I will never ordering there again.
Reason of review: Order processing issue.
Preferred solution: Let the company propose a solution.