When I have different services, offered by the same person, the time on the calendar is not blocked off for the different services: I offer online tutoring in blocks of 60 or 30 minutes. If I get a booking for 5pm for the hour session, another user is able to book at 5pm for a half hour session. How can I prevent this?  If it can be solved, I will be far more likely to purchase the add-on for payment and calendar integration.