Uber driver got away with my phone.

I had a phone lost in an Uber, soon as I started contacting the driver after a tedious time spent trying to contact Uber and downloading the app, my phone was eventually switched off. The driver said it was him, it was the passenger he picked up next and when we tried following up the story he stop contacting me. The irritating part is there’s no way of contacting him without Uber as the middle person and they kept saying I have already contacted the driver so that’s that. Uber is letting it’s employees to get away with this without proper investigation in the matter.