You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Can you please help me to change my existing reservation?

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

USER: Sure, I am Janet Perez.

ASSISTANT: 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 checking.

ASSISTANT: Thank you for choosing us.