This depends on whether you have booked the bus trip as a connecting trip. This is when you book a single trip between your departure point and your destination point that involves two or more buses (this will be shown on the booking search form) and don’t book two separate trips that you expect to connect.
If you have booked a connecting trip, then the reference number will have a “C” in front of it. In this case, the second bus will wait if the first bus is late.
If there is no C, then you have booked two separate trips, and there is no guarantee that the second bus will wait if your first bus arrives late. We are not able to arrange for the driver of the second bus to wait if the first bus is late. For this reason you should always book the trip as a connecting trip.