You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Please provide your name to search your ticket from our database.

USER: Helen Walker.

ASSISTANT: We regret to inform you that there is no active reservation found on your name.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for contacting us.