You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,.

USER: I am Ryan Roberts.

ASSISTANT: How can I serve you today?

USER: I would like to change my existing reservation. Can you please help me in this?

ASSISTANT: Sure, I am here to aid you.

USER: Thank you.

ASSISTANT: Please wait for a while, I will check with your reservation and get back to you with the status.

USER: Sure, I will wait.

ASSISTANT: Thanks for being patience, we did not find any reservation with your name in our data base.

USER: Not a problem, thank you.

ASSISTANT: Thanks for approaching us, hope to serve you again.