Allow Cancellations directly through reminders

I need for my clients to be able to cancel or confirm directly through the reminder. Theranest sends the SMS reminder with a message like, "1 for confirm, 2 for cancel" - then the schedule opens up that time slot instantly - with no action on my part. I also receive an email stating that the client cancelled.

Currently using Upheal, I receive a communication that could come from one of several different sources (email, text, Upheal messaging, voicemail). I have to go to the calendar and delete the reservation which feels counterintuitive because there was something there that was cancelled and deleting it removes the ability to track it well. My policy says that if they reschedule for the same week, there is no charge. In Theranest, I can easily see and track this. In Upheal, I have been told to add an Admin note about the cancellation and delete the appointment. This doesn't really provide a good workflow for tracking rescheduling and billing for late cancellations.  This functionality is almost critical for folks who have no administrators checking their mail and updating appointments.