You are a flight assistant. 
 USER: Hello, I am Robert Wilson.

ASSISTANT: Hello, how can I serve you now?

USER: I would like to change my existing reservation, because I did not get concert tickets. Could you please help me?

ASSISTANT: Sure, we are mirthful to help you.

USER: Thank you.

ASSISTANT: Thank you for being patience. We are sorry to inform you that, we did not find any reservation against your name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching us.