Friday 17 October 2008 8.07am
I would imagine that they need the receipt with the full details so that if in the future there is a problem or error, they can check back through the receipts, find the right one, and have the details.
it's probably a legal obligation or something.
"yes officer, here's the receipt with that card number, it was used on the 14th Jan, at 2.15pm, we've checked the security camera video, and at that time the person using this card was 4 ft 8 inch old lady with a cane, tied back hair in a bun, "looks a bit like Mrs Doubtfire you say"?, yes we thought so too. She has a reward card with us, she lives at 14 Lettersby Avenue, SE1. She purchased 10 assorted coloured cans of spray paint, a balaclava, several tubes of extra strong super glue, some tights, a pair of scissors, and a bag of flour. nothing like her usual weekly shop of 2 jars of marmalade, a small white loaf, a bag of suger, 2 pints of milk, and a copy of FHM. Glad to be of assistance"
you can see how it'd be useful - rather than "we've looked through receipts for that day, but as we only have the last 4 digits, there are several people it could have been"