You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I be at your service today?

USER: I want to change my existing reservation which is done recently due to some health issues, can you please help me in this?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Sure, my name is John Miller.

ASSISTANT: OK, please wait for a while.

USER: Sure, I will wait.

ASSISTANT: Sorry we could not any reservation on your name.

USER: Ok, no problem. Anyways, thank you for your service.

ASSISTANT: Thank you for approaching us.