Yep That has happpened to me with a VISA RBS debit card. I spoke to a member of the RBS team investgating this Some payments to amazon are going through Europe and as such a foreign currency charge is being levied. It has happened to me 7 times, one with pay-pay, six with amazon. You need to watch out for this as the bank will stop refunding at the start of March. Speak to the bank if you want you money refunded, but you will need to contact Amazon customer services about this if you dont want it happening again.
I had the same problem, and I argued over it with AMAZON.CO.UK and Natwest. Both said that the extra fees were not charged by them. I had given up on the issue, but I received the refund yesterday. I guess AMAZON and Natwest have negotiated and the later decided to return the extra transaction fee. I hope everyone who was charged the fee has receive refund, too.