A Spanish bank, Bankinter, is testing what it says is a world first: a Visa credit card with a three-month lifespan that costs nothing and runs up no interest. The "holiday card" - promoted initially to the bank's existing credit card holders via a mailing - is marketed as a way of controlling expenses for a specific purpose. In this case, it would be a vacation. But the bank is also looking at future alternatives such as a "Christmas card" or one to handle high-cost family events like weddings. At the end of the three months, customers can decide whether to pay off all or some of the balance or to convert it to a personal loan. Grey Advertising is the agency.