You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Gary Thompson.

ASSISTANT: How can I aid you today?

USER: I want to do some changes in my existing reservation, can you help me for that?

ASSISTANT: sure, I will help you to change your reservation.

USER: Thank you.

ASSISTANT: Please give me a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, I didn't find any reservation on your name in our database.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome, thank you for reaching us.