What can you do about it?
First, don't accept that the caller is who they say they are. Take notes, and then verify the information they gave you. A real Microsoft Certified Professional will have a verifiable MCP number. They should be able and willing to give you their:
- Transcript ID
- Access Code
With these two pieces of information, you can look up their certification with Microsoft.
https://mcp.microsoft.com/Anonymous//Transcript//Validate
If their information doesn't match, they're lying to you about who they are, and probably everything else.