Large Shops have what is known as a "Floor Limit" above which things need authorisation. This is, mainly, due to the sheer volume of transactions. So the card details are only checked against a hot cards file, and left to sit to be authorised later that night. This can be quite a small limit, so it stands to reason, that if they are charged 50p for a debit card transaction, and you've spent
( Alex Save a Tree, Eat a Beaver!, Sun 13 Nov 2011, 2:06, Reply)