You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how can I aid you?

USER: I am Margaret Garcia. I want to change my existing reservation due to some health issues. Can you please help me?

ASSISTANT:  Ok, please wait I will revert you.

USER: Sure.

ASSISTANT:  Sorry, no reservation was found on your name.

USER: Thanks for your kind response.

ASSISTANT:  Thank you for availing us.