Qualifying this as an IT story because it took place on a software package (hey, it's a less tenuous link than some of the articles on here!)
Client: Ok, so we've invoiced the same shipment three times and given them to the customer
Support: Since you've given them to the customer, they're a legal document, you'll need to issue a credit note for two of the invoices
Client: I can't do that, only one's been paid, I can't issue a credit note if the invoices are unpaid
Support: No, you'll be issuing the credit note's to pay off the two invoices
Client: No, I'm telling you, I can't issue a credit note if the invoice isn't paid.
Support: Why not?
Client: Well every time I issue a credit note, it asks if I want to generate a refund, I can't refund him if he hasn't paid.
Support: Sir, why don't you click no when asked if you want to refund him?
Client: I can do that?
Support: Yes, why do you think it asks Yes or No
Client: oh... bye!