well, maybe with corporate account, but I can't say anything because I'm not informed about those kind of accounts.
but for everyday customer, if you have your phone still one the warranty, you won't need any credit cards, you'll simply need your phone with the serial number, go to an apple store and change it right away (exept liquid damage or physical damage, of course).
also, maybe for other smartphones, but for the iphone because of the huge demand, I got a lot of people coming from Bell, Rogers, Fido and Telus, ect. Even after one week of purchase.
most of the time because they just don't have them in stock.