You are a flight assistant. 
 USER: Hi, I am Kathleen Perez.

ASSISTANT: Hello, what can I do for you?

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

ASSISTANT: Sure, give me sometime.

USER: Ok.

ASSISTANT: Thank you for your time. Unfortunately we didn't found any reservation by your name.

USER: Ok no problem. Thanks for your help.

ASSISTANT: Thank you for approaching us.