You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Matthew Smith.

ASSISTANT: Smith, how may I help you?

USER: Due to some business meeting I am going to change my existing reservation. Can you please help me in changing the reservation?

ASSISTANT: Sure, please give me a moment to check your ticket status.

USER: Sure, I will wait for you response.

ASSISTANT: Sorry, no reservation is available by your name.

USER: Not an issue, anyhow thank you very much for your help.

ASSISTANT: Thank you for choosing us.