Pitney Bowes , again I don't have the foggiest idea what that is.
Pitney Bowes is the company that receives, repacks and then ships items for delivery abroad under eBay's GSP.
Provided you have tracking proof of successful delivery to Pitney Bowes, eBay itself will be liable for any refund claim the buyer makes for non-delivery or damage.
The money back guarantee case may be directed to you initially. You need to enter your tracking number and point out that loss or delay in international shipping to your buyer is eBay's responsibility.
In the hopefully unlikely situation that the buyer leaves you negative feedback you would be able to get this removed by eBay customer support.