Are you still unable to take an exam on the booked date? You can initiate rebooking by clicking on the relevant exam in the account. You can then choose the rebooking option. The rebooked exam must then take place at the same location as the original exam.
Note: From January 1, 2018, it is only allowed to rebook an exam a maximum of twice, and this must be done at least two days before the exam date.