ur not alone

happened to me last year when i was taking my second attempt. let me know if u have any doubts on this... i can help you out...
If u are yet to reschedule your exam...
GMAC is otherwise helpful yet rigid about their processes.. u will need to select a center and date of your choice from the slots available on the net... (they wont accomodate you for the date and time u need if its not there on the site) but they'll wait for another week if required to see if a slot opens up in the center of your choice during the mentioned date period.
but if you have already then good luck!!