Apple India — macbook repair

I was gifted an apple macbook by my brother in the us. It is still under warranty but the service centre told me the warranty was voided due to a dent on the body. This dent is almost invisible and i know how well i have been taking care of it. I was hardly able to use for a few months and now am being asked to pay 46 000/- to have it fixed. This is more than prohibitive for me and i was hoping you would look into the matter.