I work for Wal-Mart, in accounting. Yes, we can look up reciepts for customers, but we need to know the exact day the purchase was made. There is not an option in Wal-Mart's outdated electionic journal program to just search for credit card numbers. The search has to be pulled up day by day, which can take a long time.
You must also be sure you have the correct store. Each store can only access their own electronic journal history. I can't tell you how many times a customer has called to see if we can locate a reciept for them, and after hours of searching, they finally realize that they purchased the item at the store five miles down the road.