You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: My name is Frank Mitchell.

ASSISTANT: How may I serve you?

USER: Due to health issues, I just want to change my existing reservation. Can you please help me?

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Thanks for your time, there is no reservation found on your name.

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

ASSISTANT: Ok, thanks for reaching us.