UPS Worldwide Saver® package never arrive. UPS open case and refuse to compensate for lost package Springfield Gardens New York

My friend purchase item volume $800 on website and send to my address by UPS. Tracking 1Z8X99970440127811‏. I never received item. According to UPS, package was left on front door. I live in apartment building, right now my building under construction without any building security, no cam, nothing. According to UPS package was left after first visit, usually when nobody home UPS put sticker on front door and after 3d visit customer must pickup package in UPS facility. I call to UPS and open investigation case, after 10days my case was close.

I spoke to UPS customer service Natalie. Natalie told me case close because UPS have my signature on proof of delivery. I never sigh any paper or proof of delivery and ask Natalie to send me copy of my signatures.  Natalie refuses to provide me with copy of my signature and told me I have to open new case. To open new case senders were was purchase item must contact UPS. Sender located in Philippines and refuses to open case. This problem exists more than 1month. I need somebody to resolve this. I never sigh any paper. UPS should never left unattended package in apartment building without security.