I have a (first time) customer with a $600 order who we shipped with signature required USPS priority. Tracking shows delivered to correct address but is signed "Covid-19" and she is stating she did not receive. Customer is requesting a refund which we have denied and have asked her to open claim with USPS. She is opening multiple support tickets, threating us with lawyers and social media posts, blah blah blah, at this point because of the threats and her behavior we had to blacklist and suspend her support ticket access. She also paid using an installment plan provider which normally sides with the merchant in these cases. Just curious if you think we are in the right and what do you guys usually do in these cases? I feel bad for her, but we finished our obligation by shipping the product timely and with signature required.