Thanks for the replies above.
I guess the only way to figure everything out is to go throught he order emails and tally up the figures. Will report back if any interesting pattern shows up.
I looked into my account page and found that the gift card monies are being stored as Hong Kong dollars... It's interesting that I bought the gift card in Aussie dollars and then loaded it up in the Indian store but it is saved as Hong Kong dollars. Until recently I'd only been buying books in Hong Kong dollars and they can tell from my IP address I'm in Hong Kong...