The funny thing is i had two problems with purchases under £100 using my mastercard , one was a purchase from hong kong and when i phoned up they refunded me the full amounts , seemed to want to help much more then the banks using debit cards.
For example a similar situation to gav989 mastercard told me that the retailerl whether in the EU or international, had to arrange return of the item and associated costs which they had 14 days to arrange otherwise i was free to dispose or keep the item with a full refund
You still have protection for purchases under £100 via credit cards because you are not using your money to purchase, unlike debit cards.