Guest: "I want to pay my card"
Me: "sure, go ahead and insert it."
Guest: *starts to insert their debit card*
Me: "oh sorry, start with your redcard"
Guest: "but I want to pay this card"
Me: "if you want to pay your redcard with that card, insert your redcard first"
Guest: "no, I called and they told me I should pay $30 on this [debit] card"
They ended up leaving. I still can't figure out what they meant. First of all, we obviously can't pay off non-Target cards, second of all, you don't pay off a debit card. I was so confused. Normally I can at least figure out what they mean, but this time I have no idea.