Delhivery courier - Theft of items

We had sent three packed to our customer, each packet had six items with delivery challan. Two package delivered perfectly but third one delivered with *items missing.

Someone from Delhivery stole three item and repacked packet and delivered it.

Now Delhivery is saying the will mention package as lost and give us claim as per agreement which is around **** but actual value of loss item was more than *****.

I said when packaged was delivered how can you claim it as lost, someone from your team stole the items and delivered it. They are not providing any proof of weight.

AWB no. **************