Hi there, yes I was able to book a new appointment after about two weeks or so. I cancelled my July 17 interview on May 24th or so, and on the 13th June interview dates for 17-20th July became available and I rebooked. I had checked daily up until then and there was nothing at all showing up, so they get released at random times. The button was a reschedule button, but by selecting that and going through it will basically cancel your appointment so that you can then book another one when it becomes available.