If you go to the 'delivery history' page on your account you will be able to see all of your previous payments. You might also notice at the top of the page we show you your current balance as of this week.
When we take payment for your box, this is placed as a credit on your account to go towards your upcoming order. There's no need to panic if your balance shows a negative number, this is actually how our site recognises that it owes you an order for that amount. When your account is charged for your delivery, this number will revert to 0.
If you ever have any extra credit placed on your account, this will also show as a negative number in your current balance and we will use up that value first before taking any further payments.