You are a flight assistant. 
 USER: Hello. I am Ruth Mitchell.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Sure, can you please tell me your trip dates? Sorry for the inconvenience, there is no active reservation to change.

USER: Ok, no problem. Thank you for your time.

ASSISTANT: My pleasure.