I walk in the store with the items in one hand and receipt in the other. After standing in line for five or so minutes, I handed both the receipt and the items over the cashier where she eyeballs the items and the receipt. She then asks for the credit card that I used for this purchase. For those who are familiar with an item return process, the printed receipt usually provides the last 4 digits of the credit card that you used for that purchase. If the credit card you presented to that person does not match the last 4 digits they either deny your return or you can ask for store credit depending on the mood of the cashier.
When the cashier inspected my card, she told me that the numbers didn't match. I must have given her the wrong card but my other card still didn't give a match. At the back of my mind, I was already thinking about some reasons why the match didn't happen;
- I gave them the wrong card.
- Their system fiddled with my numbers
- Both last 4 digits of the card didn't match what's on the printed receipt.
- I used an American Express card to buy the said items the day before
- I have two different American Express Cards
For the first test, the cashier scanned CARD A on her terminal. The last four digits on the printed receipt and my card matched. For the second test, I scanned CARD B on the customer terminal and that yielded the same results as the first test. For the third test, I used CARD A that so happen to have an RDIF tag. Eureka! The numbers on the receipt didn't match what was on my card but matched what was on the returned item's receipt. I spent $0.33 per test, plus 7 cents tax for a total of $1.06.
The manager finally walked in and confirmed that if you use an AmEx card, the RDIF scanning system only takes 16 digits and since American Express only has 15 digits, the systems will generate a 16 digit number and print the last 4 digits on your receipt. This confirms my second assumption that yes, the system indeed fiddled with the numbers on my card.
This was all done within 7 minutes and I was out of the store with my refund in hand and some sweets for the kids.
- The "Item Returns Oracle" has been proven that it was not an Oracle but a Heuristic. The third test proved this.
- If the cashier asked for the manager in the first place, I could have gotten the return earlier. I think this might be a simple deviation of Adam Goucher's "Know Where The Sun Is Heuristic".
- Black Box Testing of a Financial Transaction system doesn't have to be expensive.
She is THE shopping expert in our household :-).
EDIT: I was aptly corrected that Oracles are Heuristic based. I agree. My reason for calling it as an oracle was due to the cashier's insistence that the receipt will "always" print the last 4 digits of the user's credit card.