Evri has failed to deliver parcel

Could anyone offer advice as to how I deal with a failed delivery? The tracking shows the parcel was out for delivery but this was then updated to show failed delivery due to package being damaged. I have raised an enquiry with Evri and my buyer has the patience of a saint but as yet there is no sign of the package. I just feel that neither I or the buyer is at fault here but they will require a refund