listing available appointments only in appointments +

I am using appointments +, I want to list specific appointment times, the plugin seems to require that you set specific block times, I run classes that take 30 minutes but don't start on the half hour as the calendar shows, ie, some start at 12.45, some 5.40, some 5.30 etc, so in order for me to make this work it requires me to set the base number of minutes to 5, this would show an extraodinary number of times blocked out and a lot of scrolling to find them. Is there any way to show only the appointments which are available for booking and not show those which are not ?