You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: Due to some emergency issues, I would like to change my reservation. Will you please help me in this?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Let me know your name to check your reservation?

USER: Sure, I am Melissa Perez from Boston.

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 issues, thank you.

ASSISTANT: Thank you for choosing us.