Hi Ihtisham Mughal,
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
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if the reply is helpful--