I had a problem where they stole my mailbox. I went to the USPS and UPS and they gave me a proof where it was stamped that was for me to withdraw in the leasing office, I returned to the office and until now my package did not appear!

Contact the company came from and find out which UPS or United States Postal Service delivered it and if it requires a signature who signed for it

Ask both USPS & UPS to email you coordinates for packages (if they try to tell you they can't it's a lie, ask for a manager). Whenever they scan the packages to be delivered/handed over, it gives the exact coordinates of where they were when they scanned them for delivery. You can use that to see who's telling you the truth and in court, if needed. Hope that helps.