You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, How can I help you today?

USER: I am Mary Wilson.

ASSISTANT: Ok.

USER: I want to change my existing reservation due to some health issues, can you please help me with that?

ASSISTANT: Sure, I will help you with that. Please wait a while.

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: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for choosing us.