You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my reservation which is done recently due to some problems, can you please help me?

ASSISTANT: Sure, can I know your name please?

USER: Ok, my name is Frank Clark.

ASSISTANT: Ok, wait a moment please.

USER: Sure, I will wait.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: Ok, no problem.

ASSISTANT: Thank you for approaching us.

USER: Thank you for your service.