IIBF — Late transaction failed message and due to which I have to pay extra fee and preferred center is also full now

It's totally unfair . i made payment for JAIIB exam, now after 10 days i get the message of transaction failed ...what is this?????
and now the center capacity is full ans also i have to pay extra late fee now

plssssssss help me out
call me [protected] plss

i want to give this exam in may only