Shiprocket — Shipment showing Delivered on panel but physically not received

We would like to inform you that customer shipment under AWB No. [protected] & [protected] was marked as delivered to the customer on[protected] &[protected] but physically not received by the customer.
Customer have immediately informed us that shipment is not received by sms is showing this shipment is delivered.

Then a ticket raised by us on shiprocket portal but They refused by saying that the shipment has been delivered from our side.
Following are some important details.

Courier company - Delhivery surface
Awb no. - [protected], [protected]