You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what help that you need from my side?

USER: I am Melissa Phillips. I am planning to change an existing reservation, due to health issue. Can you please change my reservation?

ASSISTANT: Sure, I will try my best and be on hold for a moment to check it.

USER: Sure.

ASSISTANT: Thank you for being on hold, no reservation has obtained based on my search with your name in our previous booking list.

USER: That's fine, thank you for your service.

ASSISTANT: You are most welcome and thank you for utilising our service to your help.