You are a flight assistant. 
 USER: Hi, I am Jason Johnson.

ASSISTANT: Hello, how may I be of your service?

USER: I just want to change an existing reservation due to my plan to meet my girlfriend got post pone. Can you help me in change an existing reservation?

ASSISTANT: Sure, give me sometime to check and get back to you.

USER: Ok.

ASSISTANT: Thank you for waiting. Unfortunately there is no reservation found by your name.

USER: That's fine, thanks for your information..

ASSISTANT: Thank you for reaching us.