When processing a refund for a web order, there is nothing that let's you know if you have selected the wrong tender type. A mistake that only gets flagged if the customer realises. A pop up box that warns you that you have selected the wrong tender type would be useful. Then, if you meant to, for whatever reason, you can continue. But if it was an error, then you can go back and correct it. Thinking about it, this would be useful on our retail tills too.