Delivery and Courier Dispatch System

We are looking for a developer to build a delivery and courier dispatch system for our growing service. Every day we take dozens of orders from several channels, and right now we split them between couriers by hand using spreadsheets and chat apps, which leads to confusion, late deliveries and lost requests. We need a web application where a dispatcher sees every incoming order in one feed, assigns a courier with a single click or through automatic matching rules, and instantly pushes the task to that courier. The courier works from a mobile interface: receives the address, gets a route and moves the order through statuses from accepted to delivered. On a shared map the dispatcher watches the position of all couriers in real time and checks their workload and time on the road. Reports are essential: number of deliveries, average speed, delays and revenue per day and per courier. We also need access roles, a change history and status notifications to the customer. We expect a clean interface, stable performance under load and clear documentation. Please share your relevant experience, a rough estimate and your proposed milestones.