Shiprocket — Denying service using policies and refusing refund for lost items

I have shipped products to ahmedabad adn they are lost and shiprocket is denying to do anything using their policies and refusing the refund. Plus, whenever i am talking to them and asking them questions, they just cut the phone (FYI, they say that they can't cut the phone).

Incident
Order creation date: 28 Apr | 17:11 PM
Delivery place: Ahmedabad, Gujarat
Problem: Shiprocket's courier partner xpressbess took the shipment and marked it delivered. We sent the our product as sample for a business deal to vendor in Ahmedabad (we entered the amount as zero to avoid confusion at later stage during bookkeeping activity). The item was marked as delivered and after few days we got to know that it was falsely marked as delivered. We got to know about this incident after 3 days and shiprocket told us to reach the courier service to ask about the delivery status. After more than 30 days, it was confirmed that the parcel was lost and when we asked the refund of the product and the shipping fee, they asked us to reach out to the Shiprocket.
Now they are denying us all the services saying that they can't do anything and told us to reach out to them before hand (within 72 hours). Basically, they are asking us to reach out to all the customers and confirm whether the item is delivered or not even if the tracking is saying it is delivered.