You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I want to change my existing reservation due to bad health issues. Can you help me with that?

ASSISTANT: Sure, may I know your name?

USER: I am  David Lopez.

ASSISTANT: There is no active reservation on your name.

USER: Ok, no issues. Thank you for your kind information.

ASSISTANT: Thank you for oping  us.