Mumbai Customs — Customs Duty charged incorrectly more than the cost o[censored]sed laptop

Customs Duty charged incorrectly more than the cost o[censored]sed laptop

I have sent a laptop which is 7 years old and the cost in Australia is 100$ for that laptop. I have mentioned the same in my courier value and still in India the customs has charged 6000/- Rs for this item.

I have sent to my cousin's kid as they are doing home schooling for long time and instead of tab or mobile laptop would be better option.

I want to understand how do the customs work on used goods.