Uber doesn't care about its customers

My driver drove away with an expensive personal item and I told Uber and they refuse to intervene and keep telling me to speak to the driver directly, but he never answers his phone. They have sent him requests to call me, but he hasn't called me. This constitutes theft and they should hold the driver liable, but all they can say is"phone the driver ", they are really inconveniencing me because I need the item for work, but it seems they have better things to do with their time than deal with a genuine customer complaint appropriately.