You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I provide assistance for you today?

USER: Can you help me to change the reservation which I had done recently?

ASSISTANT: Sure, may I know your name to check with your existing reservation status?

USER: My name is Alexander Nelson.

ASSISTANT: Ok, please wait for few minutes.

USER: Sure.

ASSISTANT: Sorry to say that there is no existing reservation found on your name in our data base.

USER: That is ok, thank you for assisting me.

ASSISTANT: Thank you for reaching us.