Microsoft Certification Program is supported on their own forums. 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
Hope that helps.
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