Shiprocket - delivery delayed led to cancellation of order

My customer ordered from Shivpuri, MP. I sent the parcel through Shiprocket on * September from Vadodara, GJ. It had to be delivered on *th September but It was misplaced and it reached Vijaynagar, AP. There was Operational Constraints delayed * days and was told to deliver by **th September, the order did not move from its place and the last location is still Vijaynagar, AP. Now my customer has Cancelled the order out of frustration and when I asked that I should be refunded for this. When I ask them who is responsible for delivering goods at right time to customers they Don't actually reply with a proper answer. They don't have any policy to deliver on time and Don't care if their customers lose their Order