Ordered an iPad Smart Cover with the iOS Apple Store app. Bank declined the transaction according to email from Apple. I found out why: I had used the app to check the specifications of a MacBook Pro and had accidentally hit the "Buy" button. When I added the Smart Cover, the purchase process was finalised. Repeated attempts to reauthorise the credit card failed, this was when I spotted the MBP on the transaction list. I removed the offending item as its price exceeded my daily credit limit by over 50%.
Apple has confirmed the update of the order.
#Phew.