They are not enrolled in MBP
Confirm the email they are using to sign in. "Can you confirm the email are you using to log in?"
Send password reset to primary email on profile
Change the email to something you have access to and tell the agent their temporary password.
Swap email to something that is already on the profile (secondary email)
After Exhausting all other options, create a bug ticket.
Email your Team Lead
"Oh my God!" Pennies
"Oh My Lanta." Pennies
"Oh My God!" Dollars
"Great Gravy....." Cents