Hi guys, just wondering if anyone could give me some quick thoughts...

I sent an item via a letter and the buyer has let me know their item was not received...I would be wary as this buyer has not received something once before but it turns out I have one more item left despite the fact I sold out of it on Ebay.

Did I make a mistake and cause an unlucky coincidence? Or did I mess up someone else's order? I'm planning to just replace the 'lost item' since I have one left...is this what you would do? I'm kind of worried someone else is going to email me and go...you sent me the wrong thing! Thanks in advance 🙂