OP, do you know someone who speaks good English? I suggest taking someone with you to the store to speak with the manager. As I stated previously UPS is the worst, even if you insure for the full value they will give you a hard time if it's lost. The only thing that you can do now is keep contacting them to look for the package and maybe one day it will show up. My package was lost for months and they found it at the sorting facility 4 months after losing it.
to be very diligent... what happens to packages that go unclaimed??
I heard it goes into auctions? Like everyone advised, I would keep asking them to search for it and to see what options you have to claim for insurance and such.