You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: My name is Jeffrey Johnson.

ASSISTANT: What help is required from my end Jeffrey?

USER: 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: Sure Johnson, please wait a moment.

USER: Ok, take your time.

ASSISTANT: Sorry, there is no reservation found in my database regarding your details.

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

ASSISTANT: Thank you for approaching us, have a great day.