That’s a bummer, but a relatively small one. You could get someone to weld/braze on a replacement piece, but I would be reluctant to introduce heat to it. I’d probably just fashion a steel clip to fit, and epoxy it in place.
I would certainly ask the seller/ebay for a partial refund, considering the damage together with the lack of packing. It looks like it was mailed from England to USA like that with no box? I would ask for full shipping refund + 20 percent back on the sale. Ebay should have your back. good luck, and, congrats