I recently bought a used Duster from a dealer, the odometer showed it had run only 55,000 kms. But when I took it to the authorized service center, they said it actually had done over 78,000 kms! What legal options do I have in this situation?

You have grounds to legally challenge the dealer for misrepresentation. Under the Consumer Protection Act, you can seek a refund or compensation for the difference in value due to the tampered odometer reading. You can also file a complaint with the Motor Vehicles Department for investigation and action against the dealer.