You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, How exactly I can serve you the best today?

USER: I want to change my existing reservation due to medical emergency. Can you help me with this?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: May I know your name to check your details in our database?

USER: Sure, Matthew Lewis is my name.

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: It's ok, no issues. Thanks for your prompt response.

ASSISTANT: Thank you for reaching us.