You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Jonathan Brown here.

ASSISTANT: How may I aid you today?

USER: Can you please help me in changing my recent reservation? As I'm planning to postpone my trip to some other dates due to health issues.

ASSISTANT: Sure, I am here to help you with that.

USER: Ok.

ASSISTANT: Sorry, we did not found any reservation on your name in our database.

USER: That's ok, thank you for giving the information.

ASSISTANT: Thank you for approaching us.