I'm in a dispute with Citibank at the moment over two ATM withdrawals in India. On both transactions at the same ATM I declined the conversion. Citibank is telling me that results in DCC. The image shows part of what Citibank is telling me.
It woud appear that the dispute is over less than $10. It may be easier to forget about it. The likely hood that the Indian ATM deliberaty scammed you is extrmely low. Its more likely you just pressed the wrong button.
otherwise everyone would be complaining about it. This is not even a Citibank issue, they are just passing on the info Mastercard has forwarded them,
You might be better off reporting this in the "TravelinIndia" forums. if this is a common thing there, then you will get somewhere.