I though this was reasonably clear from the above link:
Per our Exam Appointment - Reschedule/Cancel/No Show Policy, canceling your exam is allowed, and money (if applicable) will be refunded for cancellations completed more than 72 hours before the exam appointment. If the cancellation is within the 72-hour window, a late fee will be assessed, or the voucher will be forfeited.
I cancelled on 29 May for an exam on 2 July.
I then contacted ServiceNow and received this response:
"Apologies for the delayed response. It can not be refunded, however as it was cancelled 72 hours prior to the scheduled date, you may still use the voucher to schedule your exam on any day prior to 2022-08-31 without any additional cost."
