You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I am Rachel Martin.

ASSISTANT: Ok.

USER: I want to change my existing reservation due to health issues, can you help me in change reservation?

ASSISTANT: Sure, I will help you with that. 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: No problem, thank you.

ASSISTANT: Thank you for reaching us.