Blue Dart Express — My Package is lost

I was supposed to get my package delivered it to me on 22Nov2021 and was shipped on 18Nov2021 .
On 23Nov2021 I was informed by customer care that my package has been lost and cannot be found.
The person who was transporting the vehicle stopped somewhere and some one took the package it seems.
How can they be so careless ?
When I ask the customer care who is responsible for this they are telling that the seller is responsible for the package and the company is just a intermediary and is not responsible for the package.
How can they say that they(Blue Dart) are not responsible ?
They are the one to whom we are trusting and sending the package.
They need to take responsibility first and say sorry first.

Resolution for this . I need my package as my company laptop is present in it .