Appointment slot widget does not update the space available upon submit.

There are some problems with the jotform, as the form seems cannot automatically deduct the number of seats available after someone had enrolled the class.

I believe you are referring to this form http://www.jotform.me/form/80330651025444 and the appointment slot widget, correct?

Upon checking, I can see that the form has 150+ incomplete submissions. You'll have to manually complete the submissions if you want the appointment slot to be updated. Incomplete payments happens when user didn't proceed on payment process. Please see this guide https://www.jotform.com/help/272-Paypal-Incomplete-Payments-FAQ for more information.

Let us know if you have any questions or if you need further assistance.