You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: Samuel Campbell here. I want to do some changes in my existing reservation because I did not get the concert tickets, so planning to travel on another date, can you please help me?

ASSISTANT: Ok, just hold on.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found with your name to change.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: It's my pleasure.