Yeah this customer is kind of being a dick. I’ve had eBay sellers screw me worse, at least you communicated that you’re waiting for your UPS claim to give her a refund. Most sellers just tell me “carrier’s fault, I’m not responsible,” which forces me to do a chargeback if it’s a not inconsiderable amount of money. This isn’t a winning case in court (lol let’s face it, customer was just bullshitting). You showed due diligence in filing the claim. The commonly accepted practice is that once it gets a delivery scan, your part of the deal is done, and even more so if it has a picture at their doorstep, AND a signature from someone in the building/house. After that, they can try disputing with their payment processor. Anything more than that is just a courtesy. IF she got litigious, most jurisdictions require her to try to formally come to some amicable agreement in writing before filing a lawsuit and trying to serve you.
I say wait for UPS’s investigation to conclude, and stop contact with the customer unless it’s in writing (at least an email). Once someone says the “L” word, now you gotta CYA.
$300 is a lot, but even the crazies know that court costs are going to be more than that, not to mention the time investment over a sucky case
The fact that she threatened legal action before waiting for the investigation to be over just buried her hypothetical case even more lol