UPS Ups stole 1 of my luggage Nationwide

I sent 2 luggages same day and 1 was delivered while the 2nd was with the status"out for delivery" for two days. The 3rd day I was told it's missing and they're searching for it.It's almost 4weeks no trace and declared lost.Those guys opened my bag and realised the contents are worth over $6000 and decided to steal it,how can a company with such name not be trustworthy with valuables or able to trace who took lugagges out for deliveries 2 days in a row? I have sent claims of items i can remember and no response yet,though I can't get most of the items in the market again. Pls tell UPS to return my luggage or pay me the claims.