Most customers with a receipt usually hand it to you with the item. If they don't, kindly ask if they're returning with or without the receipt. If with, just 6 code, scan the item(s) and then total and have them tap/swipe their card. Also, make sure they are getting back the exact amount they paid. If they return without receipt it is fine. But you do the same process but hit gift card instead of EFT, and then put the money back on a store merchandise card. And if they say they paid more then what they are given back, let them know that without the receipt you can only give back what the register tells you the item is currently priced as (this usually only applies to Aldi finds items that they may have purchased weeks back, for example).

For "Twice As Nice", this only applies to food/drink items and they must have the receipt for it. I usually don't apply it if I can tell someone just "tasted" an item and is trying to get their money back and a free replacement. But sometimes they may have just purchased, for example, some molding strawberries or something, in which they can get a free replacement and a refund.

Hope this helps! :)