You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Alexander Baker.

ASSISTANT: How may I help you?

USER: Due to my health problem I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: Ok, please wait a minute.

USER: Ok.

ASSISTANT: There is no reservation on your name.

USER: Ok, no problem. Thank you so much.

ASSISTANT: Thank you.