Delhivery - Item was broken in transition but company refused to give insurance coverage

Hi,
I had booked an order of fragile item courier (glass painting) via Delhivery direct (AWB: *************) and taken insurance coverage also by paying additional premium. All the details pertaining to fragile item have been mentioned clearly while booking the order. The company has accepted the order, scheduled the pick up and collected the amount of courier including insurance premium. Pick up person also checked the packing of the item and collected it. However, during transition, item was broken and we have been informed by the company that item was broken and not in condition to deliver. When we asked for the insurance coverage, company mentioned that fragile item fall under restricted category so they won't provide us the refund.
If the fragile item is under restricted category then why company has accepted the order, scheduled a pick up and collected the insurance amount since details pertaining to item was clearly mentioned while booking an order. How come company collected the insurance premium for fragile item and at the time of giving the coverage mentioned about the restricted category!
Also it is mentioned on their website that they are accepting the courier for fragile item, and how they are taking care of fragile items.
After multiple follow ups they have accepted their fault however, they are not ready to pay insurance coverage even though premium has been collected.