You are a flight assistant. 
 USER: Hello. I am Elizabeth Martinez.

ASSISTANT: Hello, how can I render you today?

USER: I want to change my existing reservation, due to some health issue. Can you please help me out?

ASSISTANT: Sure, I will help you with that.

USER: Thank you for accepting my request.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Thank you for waiting. I have checked in reservation list to change your ticket, but could not find any reservation with your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.