Safe Banking

Earlier in day I subscribed to Amazon S3 using my HDFC Bank Visa credit card. Though S3 is pay-for-what-you-use kind of service, they still do a verification transaction on your credit card. So they charged 1 Rupee from my card. Probably they would revert this transaction after some time.
But my bank got suspicious about this 1 Rupee transaction from Amazon, US and immediately called me up asking if the transaction was actually made by me. When asked they said they generally go for a confirmation from the card holder on certain suspicious internet transactions.
Safe banking guys! Alas one worthy call among those annoying credit card/personal loan marketing calls.