Bookings, want to pick multiple time (different) time slots for a service at time of initial booking

Hi, 

Does anyone know how to a client can choose multiple (different) time slots in a day at time of initial booking? For example, the client needs to schedule multiple sessions of the same presentation at their site for the same day. Each session needs its own time because it will be attended by a group of people different from those that attend an earlier presentation. 

At the moment, it appears that a client needs to access the bookings page and enter required information various times in order to book the total number of sessions needed for a day. 

Please help!

GM