sat waitlist

i have registered for sat on december 2 months ago and realised today that i have mistakely choosen regular sat instead of subject tests and changed immediately it to subject tests at the same test center (which is located in a pretty rural place)so i am in waitlist for december sat subject test and my test center has avaliable seats.Is there any probability that they do not have the subject test materials even though extra seats are avaliable ?Please help me i am very nervous

@wirsindcaller If there are available seats for the SAT subject tests then they should have enough test materials for the amount of seats available.