Uber driver *****s Uber Package

I requested an uber courier for an urgent and very valuable package. The driver drove to the location and then decided to complete the trip without delivering the package. An hour later after I opened a case with Uber I get his number and he tells me that he is keeping my property and will only return it if I pay him more money. Remember I already paid uber! Now no one from uber is contactable, this man has ****** my property and is keeping it ransome!