You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: My name is Thomas Jones. 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, wait for a minute.

USER: Ok.

ASSISTANT: Sorry Jones, no reservation found on your name.

USER: It's alright, no problem. Thank you for quick response.

ASSISTANT: Thank you for contacting us.

USER: Thank you.