Appt+ Need Clients to be able to book from multiple time zones

Hi - We have a WP site running aapt+ for booking online therapy sessions. The occupational therapist lives in London but has clients across the world that book skype times with her. The current plugin is running on London time in the settings but for a user in say Sydney Australia - the times don't work and if they add to their gmail calendar - it's displays at some ungodly hour! Is there a way to work around this or a fix?