You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Alexander Smith, want to alter my reservation. Can you help me?

ASSISTANT: Sure, please wait a minute.

USER: Sure.

ASSISTANT: Your ticket is booked.

USER: Yes, I have booked my ticket in last week.

ASSISTANT: Ok, but  sorry Alexander. There is no reservation found under your name,.

USER: It's ok, I will re-check and then again I will approach to you.

ASSISTANT: Yes, sure. You are most welcome.

USER: Thank you.