or her decision by choosing the options from the simple list of alternatives the dialogue sends information on client 39 s choice to the mediator that confirms the bookings in accordance with client 39 s choices and cancels the unnecessary reservations fig4 shows a sequence diagram of an inquiry cinq 1 originated by a client using a dialogue dinq 1 sent to the mediator the mediator initiates the inquiry minq 1 which corresponds to cinq 1 and dinq 1 to booking system 1 a service provider booking system ultimately an answer dans 1 gets back to the client offering a choice which is responded to with a selection csel 1 resulting in a booking by the client on booking system 1 the mediator recognizes the potential need for a complementary service from booking service 2 and initiates an inquiry minq 2 to booking system 2 which ultimately results in a proposal including several choices dans 2 returned to the client from which a selection csel 2 is made resulting in a complementary booking on booking system 2 the bookings can be done in other means as well for instance by calling the service provider with a telephone or by visiting on site the service provider 39 s office in that case the service provider may inform the mediator about client 39 s bookings so that the mediator can inform the client on other options for example a dentist could tell the mediator that the client has booked an appointment so that the mediator may offer to book a taxi also also it is possible to add a reminder to the mediator service so that the mediator asks at certain time if the client wants to make a new booking for.