Ah, the joys of the eBay Global Shipping Program. What a bunch of schiesters to tell you that other people's property is now yours because their agent screwed up.
I have had this exact thing happen to me. What I did was open each package, because eBay rules state all items should have a packing slip. Then, I had to find them all on Facebook, and send them personal messages, because eBay didn't let me contact them directly. I got eBay support to admit on the phone that the mistake was entirely theirs, and that neither I nor the buyer should lose out financially because of their mistake. A call is better than the online chat nonsense they offer, BTW.
I am getting a bit fed up with the "convenience" of online shopping. Maybe it's just the places I go, but I never have so much trouble when dealing with real businesses. I think eBay's new policies with regard to payment by cash on collection and sharing outside contact details are going to be the end of my dealing with them. There is no way I'll pay for something I wanted to collect in person before I see it, and if it comes to selling I won't accept the level of risk that I am placed under, or the number of hoops that I would need to adhere to in order to be a successful seller. I would make far more money if I just went to work, and gave my old stuff away.
Contrast this with the pair of boots I ordered yesterday; I went direct to the factory, they took my phone number, a cash deposit, and told me they'd call when they were ready in April. A brilliant experience, and actually far cheaper than the nearest equivalent available through eBay which would probably have been far Eastern made shite anyway (Dr Martens, I am looking at you!). The boots are made by
William Lennon & Co, if you're interested!