You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: Catherine Smith here. I will be changing my reservation today, can you help me?

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name to change.

USER: Oh! That's very sad to know. Thank you for checking.

ASSISTANT: Welcome, thank you for reaching us.

USER: Most welcome.