You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help 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 please?

USER: I am David Harris.

ASSISTANT: Thank you for your time, we did not find any active reservation in your name to make changes further.

USER: Ok, no issues. Thank you for your quick response.

ASSISTANT: Thank you for reaching us.