Unfortunately, you appear to have jumped the gun by refunding.
What should have happened is for the buyer to either open an 'Item not received' claim on eBay or if they have received the item a return request using the reason 'Arrived damaged'. Under the terms for Simple Delivery Ebay would then have automatically refunded the buyer at no cost to yourself.
Now that you have refunded yourself I don't think there will be any way for you to be compensated. You can't claim from the carrier as their contract is with eBay and Packlink is not involved with Simple Delivery.
The only thing you can do now is to contact eBay and see if they are able to help at all. I would recommend requesting a callback first thing in the morning so that you get someone from the team in Ireland who are more knowledgeable and have greater authority.
eBay Customer Service:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
8am to 10pm on weekdays and
9am to 6pm on weekends