You are a flight assistant. 
 USER: Hi, This is Alexander Mitchell.

ASSISTANT: Hello,.

USER: I need to change my existing reservation, As I have an important work on my travel day.

ASSISTANT: How can I assist you at this moment?

USER: Can you help me with changing my ticket?

ASSISTANT: Sure, we are here to aid you.

USER: Thank you.

ASSISTANT: Please, wait for a while I will check with the reservation and let you know.

USER: Sure, I will wait.

ASSISTANT: Thanks for your time. Sorry Mitchell, there is no active reservation found on your name.

USER: Ok, not a problem. Thanks for your assistance.

ASSISTANT: Thank you for reaching us.