You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: Can you please help me to change my existing reservation to reserve on next week?

ASSISTANT: Sure, can I know your name please?

USER: I am Andrew Davis here.

ASSISTANT: Ok, wait a moment please.

USER: Sure, I will wait.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: Ok, Thank you for your help.

ASSISTANT: Thank you for approaching us.