Cron Job/sytist Bug?

Yesterday i canceled and deleted a booking, today that booking reminder went out for tommorows booking. Why?

The email was probably already sent to the queue to send before you canceled it.

when does it send it to the que, this was canceled and deleted a day before the email was suppose to go out. Can i access that que and delete future booking ?

At midnight. It checks for CONFIRMED bookings at midnight and add the reminder email to the database to be sent at the time you have it to send. Confirmed is a status of 2. If you canceled it before midnight it would have had a status of 3 so it would be ignored. I really don't know why it would still send it if you canceled it before midnight. 

yes I cancelled and deleted in the afternoon on the 2nd. It's happening a few times, we have had a unbearable heat wave, so rescheduling has been happening but even deleted the original date is sending reminders.