Yes, however, Xvoucher cannot assist with scheduling and rescheduling of exams, only the candidate can do that from their CertMetrics account.
Please find AWS's instructions on how to manage/reschedule your exam appointment: PearsonVUE - Exam Reschedule.
**Please Note - PearsonVUE will only allow you to reschedule twice after your initial exam appointment before your voucher becomes invalid. If this happens, Xvoucher is not responsible for providing a replacement voucher.