There are a few scenarios where you may accidentally be charged to an unintended card using Curve:
Amazon charges you when they dispatch your item(s), rather than when you place your order. That means that you will be charged on the card that is selected at the time of dispatch. In the event that the wrong card is used, you can Go Back in Time to re-map the charge from one card in your Curve app to another.
Some merchants will occasionally process your purchases "offline" - these merchants are typically hotels, airlines, Japanese retailers and American restaurants (when tipping). What they may do is send an authorisation at the time you present your card, then let it expire and then send a separate offline transaction a day or so later. This can show as 2 (or more) charges on your account - in these cases, you will only be charged by Curve once, and will not lose out on any more (Read more about offline transactions here).
Curve on multiple devices
If you are signed into Curve on two devices, you may encounter issues when attempting to change the currently selected card. In these cases, you can Go Back in Time to re-map the purchase to the correct card in your Curve app (we also suggest signing out of Curve on any other devices, too.)
Go Back in Time
If you notice that you've been charged on the wrong card, you can Go Back in Time with Curve!
Move transactions from one card to another in the app after you've paid. Go Back in Time is free to use, and you may move any purchase under £1,000 with your Curve card up to 14 days after it was made.