If you have an issue with your payment or not getting paid, you need to log in to your account at https://www.uber.com/sign-in/ or visit your local Uber hub to talk to an Uber representative.
Once logged in, visit the Help section. Under Payments and Rewards, click More. At the bottom right of all the categories, you will see Payment Review Request. Select the topic that best fits your situation, click on it and there you will be able to submit a request.