If they have cashed your payment method you are booked in. They don't normaly confirm bookings until a couple of weeks before the exam. Then its your problem not thiers if they have to change anything or you don't get your location of choice.
Same with any licenses once they take the money you have it, then you just have to wait for the single 3 ppm laser printer which does the license printing to warm up and the lic appears 10 days later.
MJ