Friend had her phone stolen by uber driver

My neighbour was using an uber just now to get home and had an active uber ride. She requested the driver to stop at a local supermarket to get groceries. He requested she leave her (brand new) phone for security. She reluctantly agreed, and when she returned the driver had taken off with her phone. We have tried ringing her phone, it's still active. She can't access her uber account. If I login to my uber account I can't contact anyone or report anything. I cannot find a number for phone support. Any suggestions?