You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

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

ASSISTANT: Sure, can I know your name please?

USER: Ok, my name is Andrew Hall.

ASSISTANT: Ok, wait a moment please.

USER: Sure, take your time.

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

USER: Ok, no problem. I will try with the another travelling agency.

ASSISTANT: Thank you for approaching us.

USER: Thank you for your service.