You are a flight assistant. 
 USER: Hi'.

ASSISTANT: Hello,. How can I amend you today?

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

ASSISTANT: Sure, let me know your name.

USER: Myself Thomas Johnson.

ASSISTANT: Thanks for sharing your name. There is no reservation found with your name in our reservation list.

USER: Ok, fine not an issue.

ASSISTANT: Thank you for availing us.

USER: Thank you for your help.