Appointments+ Time/Appointment issue

Love Appointments+. I however have a problem. We need to schedule Birthday parties that occur at 12:30 and 2:00 respectively with the same service provider. Our system is set to 30 minutes for all other appointments. How do I easily solve this problem since hours are bound to service providers not services. I cannot limit time selection to 12:30 PM or 2:00 PM? HELP! My customer does not want to switch appointment tools.