You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Jason Hall.

ASSISTANT: What service you are expecting from our travel agency?

USER: I want to some modification in my existing reservation, can you help me with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please allow me few seconds to check whether your reservation is there or not.

USER: Sure, take your time.

ASSISTANT: Sorry to tell you, there is no reservation found with your name to modify.

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

ASSISTANT: You are welcome. Thank you for reaching us. Have a nice day.

USER: Welcome.