First, what is overbooking?
'Allow over-booking' is a setting that lives under a subscription's Renewal settings. It allows customers that go over their limited number of credits per renewal cycle to continue booking, and add the cost of each additional class or appointment to their monthly renewal payment.
Are customers warned before over-booking?
Yes. Before booking a class that brings them over the limit of their limited use subscription, they'll see this message at checkout.
And this pop up if they click 'book now'.
Can customers see how many classes they've overbooked?
They can do this from their customer account by clicking Memberships > My Memberships. Notice how this subscription has a red icon on the top right that says 5/3. This means the customer has booked 2 more classes than they're subscription allowed for. All 5 classes are listed in case the customer wants to review them.
