I'd try asking for help with exam scheduling / vouchers in dedicated forums here. Participate\Ask A Question Learn / Cert Moderators will help you from there.
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
--please don't forget to
Accept as answer if the reply is helpful--