Per Adobe policy, all sales are final. Returns and refunds are not accepted.
Adobe Exam Vouchers are purchased at an exam level, not for specific exams, which provides great flexibility.
Let's say you have decided to provide 10 employees with Expert certifications. In this case, you simply buy 10 Adobe Certified Expert-level exam vouchers, and they get to choose which certification exam they will take at that level. You don't have to know ahead of time or plan who will take which Expert Exam.