I'd try asking for help with exam scheduling / vouchers in dedicated forums here. (Participate\Ask A Question)
Exams/Exam Registration/General Registration Questions
Exams /Exam Registration and Scheduling/Scheduling with Pearson Vue
Exams / Discounts/Vouchers/Special Offers / Event Offers
Microsoft Certification / Certification Profile / Transcript / Missing Exams or Certifications
Pearson VUE Customer service
Pearson VUE contact / chat
--please don't forget to upvote
and Accept as answer
if the reply is helpful--