You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Jennifer Collins.

ASSISTANT: What can I do to make your experience better with us?

USER: I want to change my existing reservation, due to some health issue. Can you please help me?

ASSISTANT: Sure, give me a moment I will check the reservation list.

USER: Ok, take your time.

ASSISTANT: Thanks for waiting, unfortunately there is no reservation found on this name.

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

ASSISTANT: Thanks for your opting us.