You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Richard White.

ASSISTANT: How may I render you today?

USER:  Will you please assist me in changing reservation, as the invitation which I got to attend for music festival got postponed?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: I have gone through the list, but no reservation is existed previously.

USER: Not an issue. Thank you for your help.

ASSISTANT: Ok, Thank you.