Hi,
You may contact Pearson VUE customer support to reschedule, assuming they are your provider:
https://home.pearsonvue.com/microsoft/contact
Additionally, please ask your question in the Microsoft Certification forum using link below. There are support moderators over there that will respond to your question in 1 business day and can assist with problems rescheduling:
https://trainingsupport.microsoft.com/en-us/newthread?threadtype=Questions&forum=mcp
Please click Accept Answer if above was helpful.
Thanks.
-TP