I got a mail that my UK appointment is on August 16, and I was informed I have a training at work, so I updated the appointment to August 30 without cancelling the previous date. I didn't don't get any mail after the update. Which date is valid, 16th or 30th?
The system allows you to change or cancel the date; you rescheduled. Simply log in to your account to see when you are meant to appear (as booking fees are not refunded for missed appointments).