You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I give provide assistance to you?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Sure, Let me know your name to check with your recent reservation.

USER: Thank you. Myself Donna Walker.

ASSISTANT: Ok, please wait for sometime.

USER: Sure.

ASSISTANT: Thanks for your time, there was no active reservation on your name to change your recent reservation.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Thank you for consulting us.