Terrible service

not for the first time, the uber driver has driven away with my phone. when trying to call my own number, it goes straight to voicemail. when trying to use the find my iphone feature, it says that the device is offline. Uber has no contact numbers or any other way of getting hold of the driver responsible. I have the details of the car and driver responsible and i would like Uber to let me know what action they are going to take. the driver was gone and the phone turned off not even 1 minute after dropping me, this indicates a conscious action to get away with taking the phone, as it has happened that a driver has previously returned with a phone after calling the phone.