Have you ever bought something only to regret it later as you run into a spending limit on the card you used? If you live in in the right country, you might have a way to overcome this particular strain of buyer's remorse. Curve is giving its British and European Mastercard users the ability to switch a purchase between credit or debit up to two weeks after the transaction took place. If you realize you're going to go into overdraft, or that you should have expensed dinner on your corporate credit card, you can make a change before it's too late.