The previous to last time I visited India I used DCU credit card for my shopping there, the bills were correct with a resonable conversation rate.
However, during my last trip I used my Bank Of America Credit Card and the conversation rates were BAD, over it I was charged 3% extra as foreign transaction fee.
Try not to use a credit card in India. If have used earlier did you observe that each bill authorization you sign full credit card number is printed on the slip!
Hope this helps.