You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I want to change my existing reservation, can you please help me in this intent?

ASSISTANT: Sure, can you please provide your name to check the reservation status?

USER: Sure, my name is Donna Hall.

ASSISTANT: Donna Hall, there is no active reservation found with your name in our database to change it.

USER: Ok, no problem, I will try with the another travelling agency.

ASSISTANT: Thank you for contacting us.

USER: Thank you for your information.