I reserved a bus tour, but I arrived late and the bus had left without me.

First, call the emergency contact number listed in the reservation confirmation email. If there is no emergency contact number, call the company that runs the tour. If you don’t know what company it is, contact the company through which you made the reservation. You must follow the terms of service with regard to refunds in the case that you were late for the designated meeting time. If the terms of service say that no refunds are possible, as a rule you will not be paid back, but if you discuss the situation as soon as possible, you might get some kind of offer from the tour operator. Because such situations can occur, be sure to call the contact number as soon as possible if you know that you are going to be late for the appointed meeting time or bus departure time.